Surgical site infection (SSI) is a potentially morbid and costly complication of surgery. We conducted this study to establish the preoperative and operative factors predisposing to SSI after gastric resection and D2 lymphadenectomy. Data on all patients undergoing gastrectomy and D2 lymphadenectomy within a 2-year period, at a tertiary reference hospital in Turkey, were collected retrospectively. The outcome of interest was a diagnosis of incisional SSI as defined by the Centers for Disease Control and Prevention. Multivariate analysis by stepwise logistic regression was then performed on those variables associated with incisional SSI. We identified 72 patients with SSI after gastrectomy and D2 lymphadenectomy. The median age of the patients was 61 years (range 31-81 years) and 43 were men. Incisional SSI was diagnosed in 15 (20.8%) patients. Of all the preoperative and operative variables measured, an increased patient body mass index was an independent predictor of incisional SSI. An increased incidence of SSI was found in overweight patients, but these infections were transient and not life threatening.