['Our objective was to assess the risk factors for surgical site infections (SSIs) in gastric surgery using the results of the Osaka Gastrointestinal Cancer Chemotherapy Study Group (OGSG) 0501 phase 3 trial.', 'The OGSG 0501 trial was conducted to compare standard prophylactic antibiotic administration versus extended prophylactic antibiotic administration in 355 patients who underwent open distal gastrectomy for gastric cancer. Various risk factors associated with the incidence of SSI following gastrectomy were analyzed from the results of this multi-institutional randomized controlled trial.', 'Among the 355 patients, there were 24 SSIs, for an overall SSI rate of 7 %. Multivariate analysis using eight baseline factors (administration of antibiotics, age, sex, body mass index [BMI], prognostic nutritional index, tumor stage, lymph node dissection, reconstructive method) identified that BMI ≥ 25 kg/m(2) was an independent risk factor for the occurrence of SSI (odds ratio 2.82; 95 % confidence interval [CI] 1.05-7.52; P = 0.049). BMI also showed significant relationships with the volume of blood loss and the operation time (P = 0.001 and P < 0.001, respectively).'] Is overweight a risk factor for surgical site infection following distal gastrectomy for gastric cancer?