To investigate the predictive significance of dynamic changes in the neutrophil to lymphocyte ratio (NLR) and platelet counts (PLTs) in patients with advanced gastric cancer (GC) during chemotherapy.A total of 259 advanced GC patients receiving chemotherapy were enrolled and grouped by high or low NLR with a cut value of 2.5 and PLT with cut value of 300×109/L. The Kaplan-Meier survival model and the Log-rank test were carried out to determine the comparison on the overall survival differences. Cox regression analysis was employed to carry out both univariate and multivariate regression studies, aiming to explore potential prognostic factors acting independently.Higher pre-chemotherapy NLR exhibited an association with metastasis and advanced grade of Borrmann type, and higher NLR of pre- or post-chemotherapy GC patients was related with Borrmann type grade. Moreover, higher PLT counts are associated with advanced grades of Borrmann type. Interestingly, patients with lower post-chemotherapy NLR or decreasing NLR hold better overall response rate and disease control rate than those with higher NLR or increasing NLR. Furthermore, patients with high post-chemotherapy NLR alone or higher post-chemotherapy NLR plus higher post-chemotherapy PLT.Our study suggested that high post-chemotherapy NLR and post-chemotherapy PLT might be adverse prognostic markers in advanced GC patients undergoing chemotherapy.Copyright: © Saudi Medical Journal.