We reviewed all first operations for cholelithiasis at the North Carolina Memorial Hospital from 1973 to 1982 to assess factors associated with postoperative morbidity in diabetics after biliary tract surgery. Diabetics (n = 126) had more frequent postoperative complications (24.6% vs. 12.5%, p less than 0.001) and higher mortality (7.9% vs. 3.0%, p = 0.02) than the nondiabetics (n = 855). Postoperative complications were more frequent in diabetics at both emergency surgery (57.9% vs. 39.1%) and at nonemergency surgery (18.7% vs. 10.2%). Diabetics were older, however, and had more preoperative renal, cardiovascular, and neurologic disease. We used logistic regression analysis to adjust for these differences and to determine independent predictors of postoperative complications. Urgent surgery, operation other than cholecystectomy, cardiovascular disease, and male sex were associated with an increased risk of postoperative morbidity. Diabetes was associated with an increase in risk that was not statistically significant. We conclude that diabetics have increased morbidity primarily because they are older and have other medical problems. The risk conferred by uncomplicated diabetes is modest, and recommendations for prophylactic surgery in asymptomatic diabetics with gallstones should be reexamined in this light.