Background/aim: The aim of our study was to compare the efficacy and the safety of the FLOT and the modified DCF (mDCF) regimens in patients with metastatic gastric (GC) and gastroesophageal junction (GEJ) adenocarcinoma as first-line treatment. Materials and methods: The medical records of 72 patients were retrospectively reviewed. Survivals and hematological adverse events of the patients were examined. Factors affecting survivals were analyzed in univariate analysis. A multivariate analysis was performed with the factors contributing to survivals in univariate analysis. Results: The median PFS (mPFS) was 10.1 months (95% CI, 6.8–13.4) in the FLOT arm (n = 33) and 7.4 months (95% CI, 9.1–21.6) in the mDCF arm (n = 39) (p = 0.041). The median OS (mOS) was 12.9 months (95% CI, 9.7–16.1) in the FLOT arm and 15.4 months (95% CI, 9.1–21.6) in the mDCF arm (p = 0.622). It was found that all grade neutropenia was 51.3% vs. 72.7% (p = 0.063), febrile neutropenia was 8.3% vs. 6.3% (p = 0.743), and thrombocytopenia was 48.7% vs. 51.5% (p = 0.813) in the FLOT and mDCF arms, respectively. Anemia was 59% in the FLOT arm and 100% in the mDCF arm (p < 0.001). Grade 3-4 anemia was 7.7% in the FLOT arm and 24.2% in the mDCF arm (p = 0.052). Conclusion: It was shown that the mPFS was significantly increased in the FLOT arm compared to the mDCF arm as the first-line treatment in patients with metastatic GC and GEJC. Hematological adverse events were more favorable in the FLOT arm than in themmDCF arm.