AIMS: Surgical site infection is the second main cause of nosocomial infections and a major complication during postpartum period. This study aimed to describe characteristics and risk factors found in puerperal women who had surgical site infection. METHODS: A retrospective cross-sectional study was conducted at Hospital Femina, Porto Alegre, Rio Grande do Sul, Brazil, including deliveries from January 2009 to December 2010. From a total of 9528 deliveries, 110 records of patients diagnosed with surgical site infection after vaginal delivery or cesarean section were detected and analyzed. RESULTS: We found a rate of surgical site infection of 1.53% for cesarean deliveries and of 1.01% for vaginal deliveries (RR 1.5, 95%CI 1.3-1.7). Among the patients with surgical site infection many had low socioeconomic status, were obese and had incorrect administration of antibiotic prophylaxis in pre-partum. CONCLUSIONS: The risk of infection was one and a half times greater after a caesarean section than after a vaginal delivery. The rates of postpartum surgical site infection found in this study, as well as some characteristics of the patients who developed infections, stress the importance of identifying potential risk factors and to seek prevention in obstetric patients through standards of practice that include proper use of prophylactic antibiotics