Abstract: Objective:To investigate the correlation among prognostic nutritional index (PNI), clinical features, and adverse reac -tions after adjuvant chemotherapy of gastric cancer patients who underwent radical gastrectomy. Furthermore, this study aimed to clari -fy the predictive and prognostic significance of PNI in patients who underwent gastrectomy for gastric cancer. Methods:This study re-viewed the medical records of148 patients with gastric cancer who underwent gastrectomy. The PNI value was calculated by serum al-bumin concentration (g/L) + 5 × lymphocyte count (×10⁹/L). The receiver operating characteristic (ROC) curve and Youden index were used to determine the cut-off value of the PNI. Survival curves were described by Kaplan-Meier method and compared by Log-rank test. The univariate and multivariate analyses were performed with the Cox proportional hazard model to identify the prognostic factors.Re-sults: The mean values of the PNI in <65years old patients ( P<0.01), T 1 and T2 stages of tumor ( P<0.01), and negative lymph node ( P=0.013) were significantly higher than those without such factors. Patients with higher PNI had significantly lower rates of postoperative complication and adjuvant chemotherapy adverse reactions than those with lower PNI (P<0.01). When the PNI value was 52.08, the Youden index was maximal, with a sensitivity of 66.7% and a specificity of 34.3%. The overall survival rate in the high PNI group was higher than that in the low PNI group (P<0.01). The univariate and multivariate analyses showed that preoperative carcinoembryonic antigen level ( P=0.018), tumor depth ( P=0.010), intravascular cancer embolus ( P=0.010), time to initiation of chemotherapy after sur -gery (P=0.034), and the PNI value ( P=0.015) were independent factors in predicting overall survival rate. Conclusion:The PNI value was a simple and useful tool to predict the prognosis and the incidence of adjuvant chemotherapy adverse reactions of gastric cancer pa-tients after radical gastrectomy.