BACKGROUND: The 2011 ACGME resident duty hour reform implemented additional restrictions to existing duty hour policies. Our objective was to determine the association between this reform and patient outcomes among several surgical specialties. STUDY DESIGN: Patients from 5 surgical specialties (neurosurgery, obstetrics/gynecology, orthopaedic surgery, urology, and vascular surgery) were identified from the American College of Surgeons NSQIP. Data from 1 year before and 2 years after the reform was implemented were obtained for teaching and nonteaching hospitals. Hospital teaching status was defined based on the percentage of operations with a resident present intraoperatively. Difference-in-differences models were developed separately for each specialty and adjusted for patient demographics, comorbidities, procedural case-mix, and time trends. The association between duty hour reform and a composite measure of death or serious morbidity within 30 days of surgery was estimated for each specialty. RESULTS: The unadjusted rate of death or serious morbidity decreased during the study period in both teaching and nonteaching hospitals for all surgical specialties. In multivariable analyses, there were no significant associations between duty hour reform and the composite outcomes of death or serious morbidity in the 2 years post-reform for any surgical specialty evaluated (neurosurgery: odds ratio [OR] = 0.90; 95% CI, 0.75-1.08; p = 0.26; obstetrics/gynecology: OR = 0.96; 95% CI, 0.71-1.30; p = 0.80; orthopaedic surgery: OR = 0.95; 95% CI, 0.74-1.22; p = 0.70; urology: OR = 1.16; 95% CI, 0.89-1.51; p = 0.26; vascular surgery: OR = 1.07; 95% CI, 0.93-1.22; p = 0.35). CONCLUSIONS: Implementation of the 2011 ACGME resident duty hour reform was not associated with a significant change in patient outcomes for several surgical specialties in the 2 years after reform.