Background: According to some guidelines for the management of gastric cancer, adjuvant chemotherapy is recommended for patients with pT3-4 or node-positive disease. The aim of this study was to define low-and high-risk groups in terms of survival, and to predict the benefit of adjuvant fluoropyrimidine plus oxaliplatin (F-OX) chemotherapy. Methods: Patients with pT3-4 or node-positive gastric cancer after gastrectomy with D2 lymphadenectomy between 2000 and 2013 were included. The performance of a previously published nomogram was assessed by discrimination and calibration. Patients were stratified into risk groups on the basis of the nomogram-predicted overall survival probability. The efficacy of F-OX within each risk subgroup was assessed using the log rank test and Cox regression analysis weighted by inverse propensity score. Results: Some 1464 patients were included. The nomogram showed better discrimination than the seventh AJCC staging classification (concordance index 0.72 versus 0.68 respectively; P = 0. 008) and accurate calibration. F-OX was not associated with improved survival in patients in the low-risk group, whereas it reduced the risk of death by over 20 per cent in the intermediate-and high-risk groups (P = 0. 036 and P < 0. 001 respectively) (P for interaction = 0. 014). Conclusion: A nomogram can aid in individualized decision-making regarding the administration of F-OX after gastrectomy for cancer.