What's Actually on the Exam? A Content Deep Dive
The USMLE Step 1 covers an extensive range of basic science topics, organized around individual organ systems and cross-disciplinary concepts1 .
Content Distribution by Organ System
| System | Percentage Range |
|---|---|
| Reproductive & Endocrine Systems | 12–16% |
| Respiratory & Renal/Urinary Systems | 11–15% |
| Behavioral Health & Nervous Systems/Special Senses | 10–14% |
| Blood & Lymphoreticular/Immune Systems | 9–13% |
| Musculoskeletal, Skin & Subcutaneous Tissue | 8–12% |
| Multisystem Processes & Disorders | 8–12% |
| Cardiovascular System | 7–11% |
| Social Sciences: Communication & Interpersonal Skills | 6–9% |
| Gastrointestinal System | 6–10% |
| Human Development | 1–3% |
| Biostatistics & Epidemiology/Population Health | 4–6% |
Discipline-Based Content Distribution
| Discipline | Percentage Range |
|---|---|
| Pathology | 45-55% |
| Physiology | 30-40% |
| Pharmacology | 10-20% |
| Microbiology | 10–20% |
| Gross Anatomy & Embryology | 10-20% |
| Behavioral Sciences | 10-15% |
| Immunology | 5–15% |
| Histology & Cell Biology | 5–15% |
| Biochemistry & Nutrition | 5-15% |
| Genetics | 5–10% |
Knowledge Application Focus
The exam emphasizes application of knowledge rather than simple recall. For example, a question might present a clinical vignette about a patient with bleeding gums and joint pain, then ask about relevant dietary history (addressing vitamin C deficiency and scurvy) rather than directly asking about ascorbic acid biochemistry7 .
Similarly, questions often integrate multiple disciplines, such as testing pharmacology knowledge through drug mechanisms rather than memorized facts about specific therapies7 .