The prognostic significance of ascites in the dissemination of metastases in epithelial ovarian cancer (EOC) is unclear. Our study aimed to investigate the association between clinicopathological factors and the development of ascites, as well as its prognostic significance. Three hundred and thirty three patients with primary EOC were suitable for inclusion. We analyzed the correlation between clinicopathological factors, including the extent of metastases, and ascitic volume. The prognostic significance of ascites was assessed using the Kaplan-Meier method and multivariate Cox's regression analysis. The average ascitic volume was 1,800 ml. Significantly, more patients with advanced FIGO stage disease presented with ascites. The volume of ascites increased significantly when metastatic disease was present in more than three regions (p<0.05), and this was the sole factor identified as associated with ascitic volume by multiple linear regression analysis. Median survival was significantly different between those with an ascitic volume less than 1,800 ml (median survival = 58 months), and those with a volume greater than 1,800 ml (median survival = 28.6 months) (p<0.05). Subgroup analysis of stage III and IV patients also revealed a poor prognosis in the presence of massive ascites (p = 0.03). Multivariate analyses found that massive ascites and poor differentiation were independent poor prognostic factors for stage III and IV EOC patients by Cox regression, using a backward elimination procedure. The volume of ascites increased significantly with the extent of metastastic disease. Massive ascites and poor tumor differentiation were associated with a worse prognosis in patients with advanced stage ovarian cancer.