"High yield" is a study idea, not an official category. The most reliable guide to what is tested is the content outline that USMLE publishes for each Step, which gives the range of questions in each area. This page summarizes those ranges so you can set your study time by evidence, not by rumor.
Step 1: by discipline
| Discipline | Share of questions |
|---|---|
| Pathology | 45-55% |
| Physiology | 30-40% |
| Nutrition | 15-20% |
| Gross anatomy and embryology | 10-20% |
| Microbiology | 10-20% |
| Pharmacology | 10-20% |
| Behavioral sciences | 10-15% |
| Biochemistry | 5-15% |
| Histology and cell biology | 5-15% |
| Immunology | 5-15% |
| Genetics | 5-10% |
These ranges add up to more than 100%, so a single question can count toward more than one discipline. By system, the largest ranges are reproductive and endocrine (12-16%), respiratory and renal (11-15%) and behavioral health and nervous system (10-14%).
Step 2 CK: by clinical science
- Medicine 55-65%, pediatrics 17-27%, obstetrics and gynecology 10-20%, psychiatry 10-15%, surgery 5-15%.
- Among the physician tasks, diagnosis (16-20%), laboratory and diagnostic studies (13-17%) and mixed management (12-16%) have the largest ranges.
Step 3
Step 3's multiple-choice items give biostatistics, epidemiology, population health and the medical literature 11-13%, a larger share than on the other Steps. See biostatistics for the USMLE and CCS.
Turning percentages into a plan
- Spend the most time on the largest ranges, but do not skip the small ones; they still appear.
- Use a QBank's reports (UWorld, AMBOSS) to find your own weak areas inside the large ones.
- Re-check the official outline each year; USMLE states the percentages can change at any time.
Read how to use the content outline and the USMLE Step 1 guide and USMLE Step 2 CK guide.