Purpose. To determine the prognosis of failing a clerkship final examination. Method. From 1994-99, 48 students at the Uniformed Services University of the Health Sciences (6%) failed the end-of-clerkship National Board of Medical Examiners' (NBME) subject exam, but otherwise had acceptable medicine clerkship performances. All of these students were retested after self-directed study; those who failed the retest were prescribed fourth-year medicine before a second retest. The authors compared median NBME subject exam scores and number of weeks of self-directed study time from the initial exam to the retest for those who passed and those who failed the retest. Results. 40 students (83%) passed and eight students (17%) failed the first retest. There was no difference between the initial median NBME score (303 versus 295, p = ns) or length of self-directed study time (25 weeks versus 18 weeks, p = ns) between those who passed and failed the retest, respectively. After fourth-year medicine, all eight students passed the second retest of the subject exam. Four of the 48 students failed USMLE Step 2. Compared with those who passed Step 2, these four students had a similar median initial NBME subject exam score (293 versus 291, p = ns), but had a lower median retest exam score (354 versus 405, p = ns). Conclusions. It appears reasonable to allow students with isolated knowledge deficiencies one attempt to retake a failed clerkship exam following a period of self-directed study. Confirmatory studies are needed.