In a retrospective study postoperative septic complications were evaluated in 140 insulin-dependent diabetic patients who underwent surgery. The data collected were matched with those of a group of non-diabetic patients, homogeneous for sex, age, and type of surgical procedure. Patients of each group were further divided into 3 subgroups according to the risk of intraoperative contamination (clean-, clean-contaminated, and contaminated procedures). Diabetic patients had a significantly (p less than 0.01) higher rate of septic complications in clean- and clean-contaminated procedures particularly of wound infections. Our experience suggests that diabetes represents an important risk factor.