Background: Peri-operative chemotherapy (POC) is one approach in treating resectable cancers of the stomach and gastroesophageal junction (GEJ). Pre-operative chemoradiotherapy plus adjuvant chemotherapy (PCRT) is a strategy under investigation with unclear outcomes. We aimed to compare survival between PCRT and POC using a large database. Methods: The National Cancer Data Base was queried for patients diagnosed between 2004 -2013 with clinical stage Ib-IIIC (excluding T2N0) adenocarcinoma of the stomach or GEJ. Patients treated with definitive surgery, POC with or without pre-operative radiotherapy of 41-54 Gy were included. Overall survival (OS) was defined from date of definitive surgery to death or last follow-up and estimated using Kaplan-Meier methods; distributions were compared using log-rank tests. 14 patient and treatment variables were used for propensity score matching (PSM). Results: 1,048 patients were analyzed: 53.2% received POC and 46.8% PCRT. The primary site was GEJ for 69.1% of cases, and stomach for 30.9% of cases. Median age at diagnosis was 60 years. The number of lymph nodes (LN) sampled were 1-14 for 35.8%, 15-29 LNs for 45.2%, and ≥30 LNs for 16% of patients. 90-day mortality was 1% in both POC and PCRT (p = 0.93). The use of PCRT was associated with a greater pathologic complete response (pCR) rate of 12.9% vs 8.1% (p = 0.01). In the univariate setting POC was associated with superior OS with hazard ratio (HR) 0.83 (POC vs PCRT, p = 0.043). OS was greater in patients who achieved pCR (HR 0.58, p = 0.002), and for gastric primaries (HR 0.76, p < 0.01). Treatment group was not significant for OS in the multivariable model (HR 0.83, p = 0.106). Using PSM cohorts, POC was associated with superior OS (HR 0.70, p = 0.015). Median OS was 45.1 vs 31.4 months, 1-year OS was 90.8 vs 84.6%, and 5-year OS 40.7% vs 33.1% (POC vs PCRT). Survival favored POC in both gastric (HR 0.41, p = 0.07) and GEJ subgroups (HR 0.77, p = 0.08). Conclusions: The addition of pre-operative radiotherapy to POC does not appear to benefit resectable gastric and GEJ cancers. Until results from the randomized setting on PCRT are known, POC should remain a standard of care.