Objective: The predictive and prognostic role of prognostic nutritional index(PNI) in gastric cancer patients with peritoneal dissemination remains unclear. This study aims to explore the role of the PNI in predicting outcomes of gastric cancer patients with peritoneal dissemination.Methods: A total of 660 patients diagnosed with gastric adenocarcinoma with peritoneal metastasis between January 2000 and April 2014 at Sun Yat-sen University Cancer Center and the Sixth Affiliated Hospital of Sun Yatsen University were retrospectively analyzed. The clinicopathologic characteristics and clinical outcomes of patients with peritoneal dissemination were analyzed.Results: Compared with PNI-high group, PNI-low group was correlated with advanced age(P=0.036), worse performance status(P<0.001), higher frequency of ascites(P<0.001) and higher frequency of multisite distant metastasis(P<0.001). Kaplan-Meier survival curves showed that PNI-high group had a significantly longer median overall survival than PNI-low group(13.13 vs. 9.03 months, P<0.001). Multivariate survival analysis revealed that Borrmann type IV(P=0.014), presence of ascites(P=0.017) and lower PNI(P=0.041) were independent poor prognostic factors, and palliative surgery(P<0.001) and first-line chemotherapy(P<0.001) were good prognostic factors. For patients receiving palliative surgery, the postoperative morbidity rates in the PNI-low group and PNIhigh group were 9.1% and 9.9%, respectively(P=0.797). The postoperative mortality rate was not significantly different between PNI-low and PNI-high groups(2.3% vs. 0.9%, P=0.362).Conclusions: PNI is a useful and practical tool for evaluating the nutritional status of gastric cancer patients with peritoneal dissemination, and is an independent prognostic factor for these patients. Objective: The predictive and prognostic role of prognostic nutritional index (PNI) in gastric cancer patients with peritoneal dissemination remains unclear. This study aims to explore the role of the PNI in predicting outcomes of gastric cancer patients with peritoneal dissemination. Methods: A total of 660 patients diagnosed with gastric adenocarcinoma with peritoneal metastasis between January 2000 and April 2014 at Sun Yat-sen University Cancer Center and the Sixth Affiliated Hospital of Sun Yatsen University were retrospectively analyzed. The clinicopathologic characteristics and clinical outcomes of patients with peritoneal dissemination were analyzed. Results: Compared with PNI-high group, PNI-low group was correlated with advanced age (P = 0.036), worse performance status (P <0.001), higher frequency of ascites (P <0.001) and higher frequency of multisite distant metastasis P <0.001). Kaplan-Meier survival curves showed that PNI-high group had a longer longer median overall surviva Multivariate survival analysis analysis revealed that Borrmann type IV (P = 0.014), presence of ascites (P = 0.017) and lower PNI (P = 0.041) were independent For patients receiving palliative surgery, the postoperative morbidity rates in the PNI-low group and PNI high group were 9.1% and (p <0.001) and first-line chemotherapy The postoperative mortality rate was not significantly different between PNI-low and PNI-high groups (2.3% vs. 0.9%, P = 0.362) .Conclusions: PNI is a useful and practical tool for 9.9%, respectively (P = 0.797) evaluating the nutritional status of gastric cancer patients with peritoneal dissemination, and is an independent prognostic factor for these patients.