Surgical residents were tested under sleep-deprived and nonsleep-deprived conditions. Three performance domains were tested: factual recall, the ability to concentrate, and manual dexterity. Sleep deprivation was defined as less than 3 hours of sleep in a 24 hour period. A randomized, repeated measures design was used. Split-plot analysis of variances was used to analyze the mean scores, and it revealed that there were no significant differences in performance in the sleep-deprived condition compared with performance in the nonsleep-deprived condition in any of the three domains tested. Moderate sleep deprivation appeared to be well tolerated by the surgical residents studied in this investigation.