Management of gastric cancer with malignant ascites is a challenge, and limited data are available. We evaluated factors affecting survival for this condition to determine factors that predict survival outcome and to develop a rational treatment plan. We retrospectively studied 5,542 patients with gastric adenocarcinoma from January 2007 to December 2012. Among them, 347 patients (6.26%) were associated with malignant ascites. The patients' overall survival was compared among the different features. Three hundred forty-seven patients (153 females and 194 males; median age, 53 years) were enrolled, including 78 (22.5%) young patients and 63 (18.1%) elderly patients. One hundred forty-three (41.2%) patients presented with malignant ascites at the initial diagnosis of gastric cancer, and 211 (60.8%) received chemotherapy. After a median follow-up duration of 10.4 months, the median survival after the diagnosis of malignant ascites was 5.2 months (95% CI, 4.8-5.6 months), and the 1-year survival rate was 16.1 %. An ECOG score greater than 2 (P < 0.001), the presence of ascites with the diagnosis of gastric cancer (P < 0.001), no chemotherapy (P < 0.001), an albumin level less than 30 g/L (P = 0.013), an ascites volume greater than 2,000 mL (P = 0.019), Helicobacter pylori infection (P = 0.010), and metastases to other organs (P = 0.037) were associated with poor prognosis, and they were all independent prognostic factors. The survival of gastric cancer patients with malignant ascites is relatively short, and ECOG score and the presence of ascites with the diagnosis of gastric cancer are the most important prognostic factors. Additionally, chemotherapy could improve the overall survival.