Background <p>Systemic inflammation and nutritional issues have been regarded as cancer complications. As indicators of systemic inflammatory responses, neutrophil/lymphocyte ratio (NLR) and prognostic nutritional index (PNI) have been recommended to be used in the prediction of certain cancer-related clinical complications. The purpose of this study is to investigate the effects of PNI and NLR on the prognosis of gastric cancer.</p> Methods <p>From 2010 to 2018, 559 gastric-cancer patients consecutively undergoing radical surgery were involved in this study. A receiver operating characteristic (ROC) analysis was conducted to determine the optimal cut-off values of PNI and NLR. Using these cut-off values, we categorized the patients into high and low PNI/NLR groups, with clinical characteristics of these two groups compared and analyzed.</p> Results <p>Low PNI and high NLR were both associated with worse OS in univariate analysis (<i>P</i> &lt; 0.001 for both). In multivariate analysis, low PNI remained an independent prognostic factor for poor OS (HR = 1.502, 95%CI: 1.135–1.987, <i>P</i> = 0.004), while NLR did not demonstrate independent prognostic significance in this cohort.</p> Conclusion <p>In patients with resectable gastric cancer, preoperative PNI was identified as an independent prognostic factor for overall survival, while NLR did not show independent prognostic value in this cohort. These findings suggest that PNI may be useful in preoperative risk assessment and patient counseling. Further studies are needed to validate these results and directly compare the prognostic performance of PNI and NLR.</p>