A prospective multicenter study of 1,032 cesarean sections was performed to identify risk factors for postoperative wound infection. The overall rate of wound infection was 6.6% (3.8% in elective cases and 7.5% following nonelective operations), with considerable interhospital variation. Obesity was recognized as a patient-related risk factor, while risk factors inherent to the obstetric situation were duration of ruptured membranes prior to operation, fetal and labor monitoring by intrauterine devices, and omission of the use of plastic draping and redisinfection of the skin before closure. Logistic regression analysis was used to estimate the influence of these factors on the probability of wound infection. Certain risk factors associated with and overrepresented in nonelective operations would explain the increased infection rates in these, and the observed interhospital variations did not differ from the expected rates when the distribution of other risk factors was considered.