BACKGROUND: The impact of resident duty hour restrictions on patient care has not been assessed. STUDY DESIGN: We studied 275 patients undergoing emergency cholecystectomy before and after duty hour regulations instituted by the Accreditation Council for Graduate Medical Education. Operations were stratified into 6-hour intervals from the time in-hospital call began. Procedure-related complications (bile duct injury, cystic duct leak, abdominal hemorrhage, trocar injury, intraabdominal/wound infection, unrecognized retained stone) were the primary outcomes variables. RESULTS: Complications occurred after 7 of 107 (6.5%) operations performed before duty hour restrictions, which was not different from 15 of 168 (8.9%) after duty hour restrictions. In both periods, all complications followed operations that began within the first 18 hours of duty. Patients with complications had longer operative times (p = 0.038) and a higher proportion of operations lasting 120 minutes or longer (p = 0.006). Comparing patients with and without complications, there were no significant differences in patient demographics, operative complexity, or PGY level of the surgeon. Only operative time of 120 minutes or longer retained significance in the multivariable model (p = 0.0023; odds ratio, 4.05; 95% CI, 1.65-9.97). CONCLUSIONS: There was no correlation between imposition of duty hour restrictions and technical complication rates in this study. Duration of operative time of 120 minutes or longer was the only independent marker, suggesting that technical complications are a function of operative complexity, not duration of duty. These data suggest that duty hour restrictions might not have a measurable influence on the surgical complication rate after emergency cholecystectomy.