COMLEX Level 2 vs Step 2 CK

DO students can take COMLEX Level 2-CE, USMLE Step 2 CK, or both. The two exams test clinical knowledge on different terms: different length, different scales, different passing scores, and osteopathic content on only one of them. Below is a side-by-side from NBOME and USMLE, with every cell linked to its source.

We tutor both exams. The Boards Professor is led by Dr. Shauhin “Sean” Moazezi, DO, a board-certified internist who trained at an osteopathic medical school and took the COMLEX himself.

By Dr. Sahith Valluru. For The Boards Professor, founded by Dr. Sean Moazezi, DO. Published October 21, 2026; updated October 28, 2026.

Side by side

Figures as published by NBOME and USMLE. Numbers in brackets link to the source list below.

	COMLEX Level 2-CE	USMLE Step 2 CK
Who can take it	Students at a COCA-accredited college of osteopathic medicine who have passed Level 1 and completed second year [4]	MD students and graduates (LCME), DO students and graduates (COCA), and eligible international students and graduates [8]
Why it matters	NBOME: passing is “required to enter into supervised graduate medical education settings” [1]	A Step in the USMLE sequence; you must meet USMLE eligibility requirements to sit it [5][8]
Length	8 hours: two timed sessions of four hours each, on one day [2]	9 hours: one testing session, on one day [5]
Number of questions	320 single-best-answer questions: 8 sections of 40 [2]	From May 7, 2026: sixteen 30-minute blocks of up to 20 questions each [5]
Score	Three-digit standard score plus a pass/fail designation [3]	Three-digit score scale with a pass/fail result [9]
Passing score	400 [3]	218, for exams on or after July 1, 2025 (was 214) [6]
Osteopathic content (OMM)	At least 10% of the exam: Domain 1, Osteopathic Principles, Practice, and Manipulative Treatment [1]	Not listed in the Step 2 CK content outline [7]
Results	Usually within two to six weeks [1]	Typically two to four weeks after your test date [9]
Attempt limits	Four scored attempts per level, and no more than four in any 12 months [4]	No more than three in any 12 months; four attempts without a pass ends eligibility for any Step [8]

Pass rates, passing standards and fees

Checked October 21, 2026. Rules change; the linked page is the authority.

Topic	Official rule	Source
First-time pass rate, Level 2-CE	92.5% of 9,096 first-time takers, 2025-2026 testing cycle.	NBOME: examination performance data
First-time pass rate, Step 2 CK	98% of first takers from US MD schools and 96% of 5,025 from US DO schools, 2024-2025.	USMLE performance data
Level 2-CE passing standard	400. Last reviewed February 2023, in use since June 2023, next review February 2028.	NBOME: standard setting
Step 2 CK passing standard	218 for exams on or after July 1, 2025 (raised from 214).	USMLE: Step 2 CK passing standard change
Can DO students take Step 2 CK?	Yes: students and graduates of COCA-accredited DO schools are eligible.	USMLE Bulletin: eligibility
Fee, Level 2-CE	$745.	NBOME: frequently asked questions
Level 2-CE percentiles	NBOME makes interim percentile scores for Level 2-CE available in September, to line up with ERAS.	NBOME: scoring and reporting
Fee, Step 2 CK	$695 for US MD and DO students and graduates (2026 and 2027 fees).	NBME: USMLE fees

Can you convert a COMLEX score to a Step 2 CK score?

Not officially. None of the NBOME or USMLE pages in our source list publish a conversion from a Level 2 score to a Step 2 CK score, and the two exams set different passing scores (400 and 218). Conversion charts you see online are unofficial estimates, so we do not use them.

USMLE vs COMLEX at every level

The comparison above is for the clinical exams, but the same pattern runs through both series. Each has three stages, the first is pass/fail on both sides, and only COMLEX tests osteopathic principles throughout.

Stage	COMLEX-USA (NBOME)	USMLE
Basic science	Level 1: pass/fail only, 320 questions in two 4-hour sessions (NBOME)	Step 1: pass/fail only since January 26, 2022, one 8-hour session (USMLE)
Clinical knowledge	Level 2-CE: three-digit score, passing score 400	Step 2 CK: three-digit score, passing score 218
Residency	Level 3: passing score 350; two days through December 19, 2026, then one day from January 13, 2027 with 240 questions and 16 clinical decision-making cases (NBOME)	Step 3: two days, passing score 200, includes computer-based case simulations (USMLE)

On pass rates the two series are close for DO students. NBOME reports a 92.5% first-time pass rate on Level 2-CE for the 2025-2026 cycle (NBOME performance data); USMLE reports 96% of first-time takers from US DO schools passing Step 2 CK in 2024-2025 (USMLE performance data). Those are different groups taking different exams, so read them as context, not as a difficulty ranking.

Which should a DO student take?

That depends on your school’s requirements and the programs you are applying to, so check both. What the official rules do say: NBOME describes passing Level 2-CE as required to enter supervised graduate medical education, and USMLE lists DO students at COCA-accredited schools as eligible for Step 2 CK. If you take both, plan your dates around both sets of attempt rules in the table.

Studying for both

• Shared core. Both test clinical knowledge, so much of your question practice serves both.
• COMLEX only. Osteopathic principles and OMM are at least 10% of Level 2-CE, so they need their own time.
• Different exam day. On test day, Level 2-CE is two 4-hour sessions; Step 2 CK is one 9-hour session in 30-minute blocks.

See COMLEX tutoring and USMLE Step 2 CK tutoring for how sessions work.

Who tutors both exams

Dr. Sean Moazezi, DO, sat every USMLE and COMLEX exam he teaches, so a combined plan comes from someone who has taken both on the same timeline. Dr. Chelsi Flippo, MD also tutors Step 2 CK and COMLEX Level 2-CE. In sessions you work mixed clinical questions, and the osteopathic questions get their own short block each week so they are not left to the last few days.