A direct, definitive answer to the chemistry credits side of the ASCP 16+16 rule — including the organic-or-biochemistry requirement, what counts and what doesn’t, and how to close any gap on your transcript fast.
To sit for the ASCP Board of Certification’s Medical Laboratory Scientist (MLS) exam through any of the post-baccalaureate routes, you need 16 semester hours of chemistry — or 24 quarter hours — including at least one semester of organic chemistry or biochemistry.
That’s it. That’s the rule. It applies whether you’re using ASCP Route 2 (MLT-to-MLS), Route 4 (5 years of clinical experience), Route 5 (international transition), or Route 6 (military training). It applies whether your bachelor’s degree is in chemistry, biology, criminal justice, or business. It applies whether you’re 25 or 55.
The full requirement is published on the ASCP BOC MLS credential page, and it’s been the same numerical structure for years. The harder questions — what “counts” as chemistry, why survey courses get rejected, why one semester of biochemistry might be smarter than two semesters of organic chemistry — are what this guide is about.
| 16 semester hours of chemistry, including 1 semester of organic chemistry or biochemistry That’s the requirement. Read on for what each piece of that sentence actually means in practice — including the courses that satisfy it, the ones that don’t, and the strategic choice between organic chemistry and biochemistry that can save career changers significant time and effort. |
Sixteen semester hours of chemistry sounds straightforward — and at the macro level, it is. But the specifics matter, because programs and the ASCP both audit transcripts at the credit-hour level.
Most US universities operate on a semester system, where a typical full-credit science course with lab is worth 4 semester hours. A two-semester sequence (General Chemistry I and II, for example) is therefore 8 semester hours.
Universities on the quarter system — primarily on the West Coast — measure credit differently. The ASCP equivalent is 24 quarter hours, which is 16 semester hours × 1.5. If you completed your prerequisites at a quarter-system university, your transcript will say something like “5 quarter hours” per course; ASCP and your target program will convert automatically.
There are essentially three common transcripts that reach the 16-hour requirement:
| Transcript pattern | Course breakdown | Total |
| Traditional pre-med / chemistry major path | General Chem I + II (8) + Organic Chem I + II (8) | 16 semester hours |
| Career-changer efficient path | General Chem I + II (8) + Organic Chem I (4) + Biochemistry I (4) | 16 semester hours |
| Biology major filling the chemistry gap | General Chem I + II (8) + Biochemistry I + II (8) | 16 semester hours |
All three transcripts satisfy the 16-hour requirement. All three include the required organic-or-biochemistry specialization. Beyond that, the ASCP doesn’t care which path you took — only the resulting credit hours and named courses on your transcript.
Buried inside the 16-hour total is a specific named requirement: at least one semester must be organic chemistry or biochemistry. This is the chemistry equivalent of the microbiology requirement on the biology side — a specialization that ASCP calls out by name because it cannot be satisfied by general chemistry alone.
General chemistry teaches the foundational principles — atomic structure, stoichiometry, thermodynamics, equilibrium, acid-base chemistry. These are essential, but they are not, on their own, sufficient preparation for clinical chemistry coursework. Clinical chemistry — the diagnostic discipline that an MLS will practice every day — is built on the chemistry of living systems, and that means organic chemistry (the chemistry of carbon-based molecules) or biochemistry (the chemistry of biological molecules and reactions) at minimum. ASCP requires one semester of either to ensure that incoming MLS students have the molecular-level vocabulary they’ll need.
The most important word in the phrase is “or.” You need one semester of organic chemistry, OR one semester of biochemistry — not both. If you have either, you’ve satisfied the specialization requirement. ASCP does not impose any preference between the two, and individual MLS programs almost always follow the same logic.
This matters because organic chemistry has a reputation as one of the hardest courses in any pre-health curriculum. For career changers who don’t need to keep medical school open as an option, biochemistry is often the more efficient path — it satisfies the same ASCP requirement with substantially less time and stress.
There’s a footnote on the official ASCP MLS credential page that most applicants miss. ASCP states that successful completion of a NAACLS-accredited MLS program, a NAACLS or ABHES-accredited MLT program, or a foreign medical laboratory science clinical training program within the last 5 years “will count as completion of 1 semester of organic or biochemistry.” In other words, if you’ve finished an accredited lab program in the last five years, the program completion itself satisfies the chemistry specialization requirement — you don’t need to also produce a separate organic chemistry or biochemistry course on your transcript.
This is most relevant to MLT-to-MLS applicants on Route 2, where the MLT program completion can fulfill the specialization requirement. For everyone else, you’ll still need an actual organic chemistry or biochemistry course on the transcript.
| Strategic choice: organic chemistry vs. biochemistry Organic chemistry: Best if you might also apply to medical school, dental school, pharmacy school, or veterinary school — all of which require organic. Two-semester sequence is standard. Difficult but valuable beyond MLS. Biochemistry: Best for career changers focused specifically on MLS or PathA. Builds directly on general chemistry and general biology. Often more accessible for adult learners. One semester satisfies the ASCP requirement. |
The ASCP doesn’t publish a course-by-course list, because course names vary across institutions. But there’s a consistent pattern in what programs and the ASCP itself accept.
For ASCP credit-counting, a lab is not always strictly required. For NAACLS-accredited program admission, a lab is almost always required. The safer answer is: yes, take the lab. Every chemistry course on PrereqCourses.com in this space includes a lab component.
| The non-majors trap This is the single most common reason career changers think they have the chemistry credits but discover they don’t. A bachelor’s degree in psychology, criminal justice, business, or education often included one or two “Chemistry for Non-Majors” courses to fulfill general education requirements. These courses are real, the credits are real — but they don’t meet the standard required for clinical lab program admission. The fix is to retake the chemistry sequence at majors level. It feels frustrating, but admissions committees are looking for evidence of preparation, not just credit accumulation. |
Spend ten minutes running this audit on your own transcript before reading further. It takes the abstract requirements and grounds them in your specific situation.
Pull your official transcript and list every course in the chemistry department. Include course title, credit hours, completion date, and final grade. Don’t pre-judge what counts — list everything, including non-majors courses, summer-school transfer credits, and AP-derived credits.
Total only the full-credit courses. If you reach 16 or more, you’ve cleared the credit-hour bar.
Even if you have 16 hours, you need at least one semester of organic chemistry or biochemistry on the transcript. Look specifically for a course titled “Organic Chemistry I,” “Organic Chemistry II,” “Biochemistry I,” “Biochemistry,” “General Biochemistry,” or similar. If neither is present, you’re missing the specialization regardless of how many other chemistry credits you have.
Most NAACLS-accredited MLS programs require chemistry coursework to be no more than 5–7 years old at the time of application. A 12-year-old organic chemistry course may technically satisfy the ASCP credit-counting requirement but fail your target program’s recency policy. If your chemistry is outside that window, you’ll likely need to refresh it — see our pillar on refreshing an expired science degree.
After this audit, applicants generally fall into one of four categories:
| Result | Status | Recommended next step |
| 16+ credits, organic or biochem present, recent | Complete | No chemistry coursework needed. Confirm with target program. |
| 16+ credits but missing organic or biochem | Specialization gap | One semester of Biochemistry I (CHEM 330) or Organic Chemistry I (CHEM 251) closes the gap. |
| Less than 16 credits, organic or biochem present | Credit-hour gap | Add courses to reach 16 hours. Typically General Chemistry I/II or additional chemistry electives. |
| Less than 16 credits AND no organic or biochem | Full rebuild | General Chem I + II + one semester of Organic or Biochemistry. Browse the full catalog. |
Once you’ve identified your gap from the audit, the next step is choosing how to close it. There are three options, and they have very different time and cost profiles.
Enroll at your local four-year university or community college, take the courses on a semester schedule, and finish in 8 months to 2 years depending on how many courses you need. Pros: in-person labs, established credibility, federal financial aid eligibility. Cons: slowest calendar, most expensive at full universities, semester-bound enrollment windows that can cost you an entire application cycle.
Cheapest sticker price (often $400–$900 per course), but with significant transfer-credit risk — some MLS programs require chemistry coursework specifically from a four-year institution. Worth verifying with your target program before enrolling.
This is the path PrereqCourses.com offers, through a partnership with Upper Iowa University — a regionally accredited (HLC) four-year institution founded in 1857. Each course starts on the first of every month, is fully self-paced, and is completable in 4–8 weeks rather than a traditional 16-week semester. Costs run $675–$695 per course inclusive of labs, and the official transcript that programs receive is a UIU transcript — the same one residential UIU students receive.
| Course | Credits | Lab | Satisfies |
| CHEM 151 General Chemistry I | 4 | Yes | 4 of 16 chemistry hours |
| CHEM 152 General Chemistry II | 4 | Yes | 4 of 16 chemistry hours |
| CHEM 251 Organic Chemistry I | 4 | Yes | 4 hours + organic specialization |
| CHEM 252 Organic Chemistry II | 4 | Yes | 4 of 16 chemistry hours |
| CHEM 330 Biochemistry I | 4 | Yes | 4 hours + biochem specialization |
| CHEM 331 Biochemistry II | 4 | Yes | 4 of 16 chemistry hours |
By far the most common gap is missing the organic-or-biochemistry specialization. The fastest fix: enroll in CHEM 330 Biochemistry I on the first of next month, complete it in 4–8 weeks, and have the transcript delivered to your target program before your application deadline. This single course closes the most common chemistry gap and adds 4 credit hours toward the 16-hour total simultaneously.
Yes. The ASCP’s acceptable education policy requires coursework from a regionally or nationally accredited institution but does not distinguish between online and in-person delivery. Online chemistry coursework from a regionally accredited four-year university — like Upper Iowa University, the transcript-issuing institution behind PrereqCourses.com — counts the same as in-person coursework.
Yes. ASCP requires “one semester of organic chemistry or biochemistry” — these are alternatives, not additions. A single semester of Biochemistry I satisfies the specialization requirement on its own. For applicants targeting MLS specifically (not medical, dental, or pharmacy school), this is often the more efficient choice.
Not for ASCP eligibility. One semester of organic chemistry satisfies the specialization requirement. Organic Chemistry II adds 4 more credits toward the 16-hour total but is not separately required. If you’re already short on chemistry credits and pursuing the organic chemistry path, taking both makes sense; if you have other chemistry credits to lean on, one semester is sufficient.
GOB courses are common in nursing and allied health curricula, where they cover all three subjects in a single semester. The credits count toward the 16-hour total, but a single GOB course does not satisfy the organic-or-biochemistry specialization requirement on its own. Programs want a dedicated semester of one or the other. If your transcript shows a GOB sequence, you’ll likely still need to add a standalone organic chemistry or biochemistry course.
For ASCP credit-counting alone, labs are not always strictly required. For NAACLS-accredited program admission, labs are almost always required. The safer answer is yes — every chemistry course on PrereqCourses.com includes a lab component to ensure the credits count for both ASCP and program admission purposes.
ASCP itself does not impose a maximum age. Individual NAACLS-accredited MLS programs typically require chemistry coursework to be no more than 5–7 years old at the time of application. Always check your target program’s recency policy before assuming older coursework will satisfy current requirements.
Non-majors survey courses are commonly rejected by NAACLS-accredited MLS programs even when they appear on a regionally accredited transcript. The fix is to retake the chemistry sequence at majors level. This is annoying but not catastrophic — a non-majors course can usually be replaced by a single majors-level course, not a full sequence.
For ASCP eligibility, yes — regional accreditation is regional accreditation. For NAACLS program admission, it varies. Some programs accept community college prerequisites; others require chemistry coursework from a four-year institution specifically. Self-paced online coursework from a regionally accredited four-year university (such as PrereqCourses.com through Upper Iowa University) avoids this risk entirely.
Chemistry courses on PrereqCourses run $675–$695 per course, inclusive of the lab component. A full 16-hour rebuild — General Chemistry I + II, Organic Chemistry I, and Biochemistry I — is roughly $2,700–$2,780 total. Compare to traditional university tuition of $1,500–$3,000 per single course. Pricing details on the courses page.
PrereqCourses chemistry courses are self-paced. Most working adults complete a single course in 4–8 weeks. Two courses run in parallel can finish in the same window. A full 16-hour chemistry rebuild from scratch — four courses — typically takes 4–6 months at a working-adult pace, or 2–3 months for someone who can dedicate full-time effort.
16 semester hours of chemistry, including one semester of organic chemistry or biochemistry. That’s the entire ASCP requirement. The harder questions — what counts, what doesn’t, organic vs. biochem, online vs. in-person — all resolve cleanly once you understand the underlying rule.
If you’re missing the specialization, one semester of biochemistry closes the gap. If you’re short on credits, two general chemistry courses get you most of the way to 16. If you need a full rebuild, four courses over 4–6 months gets you across the line. The rule doesn’t change based on which route you’re using or which program you’re targeting — every ASCP-accredited route to MLS certification points to the same 16-hour standard.
| Ready to close your chemistry gap? Browse the PrereqCourses.com chemistry catalog or use the free Advisory Service to map your specific transcript against the ASCP 16+16 requirement and identify exactly which courses you need. New sessions begin on the 1st of every month, and Upper Iowa University issues the official transcript directly to your MLS program or to ASCP BOC. |
About this guide: Last updated April 2026. Prerequisite requirements and ASCP BOC route details are drawn directly from the American Society for Clinical Pathology Board of Certification‘s published eligibility documentation. Always confirm current requirements at ascp.org/boc before submitting an application.
