Elderly patients have greater risk for postoperative adverse events (PAEs). The study examines the rates of reoperation, the association between PAEs and reoperation, and the effect of reoperation on mortality for patients 65 years of age or older undergoing colorectal resections (CRRs), pancreatic resections (PRs), and lower extremity bypass (LEB) in 2010 American College of Surgeons National Surgical Quality Improvement Program. The models evaluating associations between reoperation and preoperative factors, PAEs, and mortality were developed using multiple logistic regression. The reoperation rates were 6.41 per cent for CRR (n=11,084), 6.79 per cent for PR (n=1,606), and 15.04 per cent for LEB (n=4,170). Preoperative factors predicting reoperation included indications for surgery, procedure category, emergency status, and systemic sepsis. The PAEs most strongly associated with reoperation were wound dehiscence for CRR (odds ratio [OR], 15.286; 95% confidence interval [CI], 11.035 to 21.175) and for PR (OR, 19.656; 8.677 to 44.531) and for LEB, graft failure (OR, 28.151; 18.030 to 43.954) and organ space surgical site infection (OR, 15.753; 6.938 to 35.711). Higher rates of mortality occurred with reoperation for patients undergoing CRR (16.88 vs 5.45%, P<0.0001), PR (28.44 vs 2.14%, P<0.0001), and LEB (6.22 vs 3.05%, P<0.0001). For elderly patients undergoing general and vascular surgery, reoperation occurs frequently, is strongly associated with other PAEs, and may elevate risk of mortality for this vulnerable population.