Recently, changes have been suggested in resident working hours and conditions. Few objective data exist, however, as to how many hours surgical residents work or how they utilize their time. Surgical residents on four every-third-night general surgery services (two services in the University Hospital and two in the Veterans Hospital) kept a log of their activities divided into 15-min intervals 24 hr a day for 4 weeks. Activity for each 15-min interval was entered into one of nine predesignated categories. Residents spent an average of 95.8 hr per week in the hospital, working 85.8 hr and sleeping 10 hr. Overall, residents slept an average of 5.9 hr per night, 4.2 hr on on-call nights and 6.2 hr on off-call nights. Operating and direct patient care activities consumed 8.7 hr per day (10.25 hr Monday to Friday). Patient care activities which residents believed could be performed by nonphysicians accounted for 1.5 hr per day. An average of 1.8 hr per day was spent in conferences or independent study. This survey provided objective data regarding working hours and time utilization for our residency. Both residents and faculty found that time spent in various activities differed from preconceived notions. We suggest that program directors may find a formal survey of this type useful in assessing the structure of their own residency and in providing objective data to compare to or determine compliance with externally generated guidelines.