The purpose of this study was to determine the disease-free and overall survival (DFS and OS, respectively) in 991 postgastrectomy gastric cancer patients untreated (n = 372) or treated with either oxaliplatin-based (n = 376) or docetaxel-based (n = 243) chemotherapy and to identify prognostic factors that could help establish subgroups of patients who would benefit from such treatment. The median follow-up duration was 55.3 months (range 31.2-90.8 months). Subgroup analyses revealed that gastric adenocarcinoma (DFS 56.9 vs 53.2 months, P = 0.180, χ(2) = 1.802; OS not reached vs 70.7 months, P = 0.521, χ(2) = 0.412), but not absolute signet ring cell (SRC) carcinoma (DFS 15.1/18.0 vs 10.1 months, P = 0.171/0.259, χ(2) = 1.874/1.275; OS 21.0/26.1 vs 20.5 months, P = 0.551/0.196, χ(2) = 0.355/1.674), patients undergoing either docetaxel- or oxaliplatin-based chemotherapy had a lower risk of recurrence and increased survival in comparison to those without chemotherapy. In the mixed SRC carcinoma patients, DFS and OS of patients treated with docetaxel-based regimen had a longer survival (DFS 50.1 vs 29.9 months, P = 0.046, χ(2) = 3.987; OS not reached vs 48.6 months, P = 0.016, χ(2) = 5.854) and lower risk of recurrence and death (DFS HR 0.540, 95 % CI 0.355-0.874, P = 0.012; OS HR 0.452, 95 % CI 0.259-0.790, P = 0.005) than oxaliplatin-based chemotherapy. Cumulatively, our results indicate that adjuvant chemotherapy is beneficial and that docetaxel-based regimen should be considered for patients with mixed SRC carcinoma.