Abstract Background: Epstein–Barr virus (EBV)-positive gastric cancers have clinicopathologic differences from EBV-negative tumors and lack TP53 mutation. Serologic profiles may inform viral contribution to carcinogenesis. Methods: We compared humoral responses of EBV-positive (n = 67) and EBV-negative (n = 137) patients with gastric cancer from the International EBV-Gastric Cancer Consortium. Serum antibodies against four EBV proteins, nuclear (EBNA), viral capsid (VCA), early-diffuse (EA-D), and Zta replication activator (ZEBRA), and to p53 were assessed by multiplex assays. OR of antibody level tertiles (T1–T3) were adjusted by logistic regression. We also conducted a meta-analysis of reported anti-p53 seropositivity in gastric cancer. Results: Consistent with EBV's ubiquity, 99% of patients were seropositive for anti-EBNA and 98% for anti-VCA, without difference by tumor EBV status. Seropositivity varied between patients with EBV-positive and EBV-negative tumors for anti-EA-D (97% vs. 67%, respectively, P < 0.001) and anti-ZEBRA (97% vs. 85%, respectively, P = 0.009). Adjusted ORs (vs. T1) for patients with EBV-positive versus EBV-negative tumors were significantly elevated for higher antibodies against EBNA (2.6 for T2 and 13 for T3), VCA (1.8 for T2 and 2.4 for T3), EA-D (6.0 for T2 and 44 for T3), and ZEBRA (4.6 for T2 and 12 for T3). Antibodies to p53 were inversely associated with EBV positivity (3% vs. 15%; adjusted OR = 0.16, P = 0.021). Anti-p53 prevalence from the literature was 15%. Conclusions: These serologic patterns suggest viral reactivation in EBV-positive cancers and identify variation of p53 seropositivity by subtype. Impact: Anti-EBV and anti-p53 antibodies are differentially associated with tumor EBV positivity. Serology may identify EBV-positive gastric cancer for targeted therapies.