Background: Surgical site infection (SSI) after breast procedures may result in significant morbidity, psychologic trauma, and additional cost. A prospective study was performed to identify risk factors for infection. Methods: A case patient was defined as any patient having a breast procedure from june 2017 through May 2018 with culture of a pathogen from surgical site drainage or aspiration or with skin changes like erythema or presence of cellulitis treated by incision and drainage and/or antibiotic therapy.All patients received pre as well as peri–operative antibiotic prophyllaxis. Randomly selected control patients were matched by time and procedure. There were 40 case patients and 78 control patients.Results: The factors associated with SSI were obesity (78% of cases vs 40% of controls; p = 0.02) and older age (mean 56 years in cases vs 45 years in controls; p = 0.005). Conclusions: Host factors as well as nosocomial factors may contribute to SSI in breast procedures.