Background: Assessment of competency during residency training has received increased attention recently. There has been less attention given to the competency of residents after training. Hypothesis: Patient outcomes for alimentary tract surgery (ATS) should be similar for surgeons who recently completed their residency training compared with more experienced surgeons, indicating that the younger surgeons had achieved clinical competency on completion of their residency training. Design: Retrospective analysis of Illinois inpatient discharge data (January 1, 1996-December 31, 1999). Setting: All 205 nonfederal acute care hospitals in Illinois. Patients: The patients were 120 160 adult Illinois residents who underwent ATS in Illinois. Main Outcome Measures: Mortality rate, morbidity rate, and hospital length of stay. Results: Regression analyses demonstrated that surgeon experience was a significant determinant of mortality and morbidity rates, with worse outcomes observed for patients of young surgeons undergoing high-complexity ATS (ie, procedures other than appendectomy and cholecystectomy). Conclusions: For high-complexity ATS, there was a significant disparity in outcomes between young and more experienced surgeons, whereas for low-complexity ATS, there was no disparity. Attention to competency during residency training is warranted, especially as it relates to high-complexity ATS. Furthermore, patient outcomes provide an opportunity to assess competency after training that can complement assessments during training and together identify educational strengths and weaknesses of residency training.