To determine if sleep abnormalities occur in obsessive-compulsive disorder (OCD), 2 nights of sleep electroencephalographic (EEG) recordings were obtained from 13 medication-free outpatients with OCD and 13 age- and sex-matched normal volunteers. Patients were awake more on night 2 than on night 1, whereas control subjects had less time awake on night 1; no other differences between groups were found on sleep latency, sleep time, minutes of movement, sleep efficiency, rapid eye movement (REM) latency or amount of stage 1, 2, 3, or 4 or REM sleep. Within the patient group, total scores on the Yale-Brown Obsessive-Compulsive Scale were negatively correlated with total sleep time (r = -0.51, P = 0.07), sleep efficiency (r = -0.51, P= 0.07), and duration of stage 1 + 2 sleep (r = - 0.49, P = 0.09) but not with REM time (r = - 0.05, P = 0.87) or latency (r = -0.26, P = 0.39). Previous sleep studies in OCD have had divergent results, especially regarding REM latency; our results suggest that many OCD patients have essentially normal sleep EEG findings.