OBJECTIVES: Due to the paucity of data with respect to real-world costs of care among individuals with gastric cancer (GaCa), the objective of this analysis is to evaluate the cost of care among individuals diagnosed with GaCa in 2 large retrospective databases. METHODS: Two large integrated claims databases spanning July 2008 to September 2012 were used to identify patients ≥18 years old diagnosed and treated for GaCa. Patients were required to be chemotherapy-naïve, continuously enrolled for ≥6 months pre- and post-diagnosis, and have no other cancer diagnosis at baseline. Eligible patients were stratified into cohorts based on the presence and timing of metastasis (M) diagnosis: no metastasis (NM), ≤120 days (M1),  and ≥121 days (M2). All costs were adjusted to 2013 dollars. RESULTS: There were 5,609 (3,486 NM, 1,469 M1, 654 M2) and 3,203 (2,004 NM, 875 M1, 324 M2) patients in each of the databases, with 189 and 23, respectively, without cost data. Mean follow-up was 24 months in one dataset and 25 months in the other. Total average monthly costs at baseline were:  NM $770–$847; M1 $662–$773; and M2 $634–$1,020. Total average monthly costs during follow-up were: NM $1,631–$2,004; M1 $9,813–$9,945; and M2 $6,598–$8,465. Medical costs represented 86%, 94%, and 93% of monthly costs for NM, M1, and M2 patients, respectively. Overall, 33% of patients received chemotherapy during follow-up and mean monthly chemotherapy-related costs were $966–$1,109, $2,502–$3,079, and $1,480–$1,521 for NM, M1, and M2, respectively. CONCLUSIONS: The results demonstrate the high burden to treat this population, with the highest costs in the group with metastases at diagnosis (M1) and medical-related costs as a major driver of overall treatment costs.