This study evaluates the prognostic role of carbohydrate antigen 19 to 9 (CA19-9) in predicting survival of pancreatic cancer patients. Literature search was conducted in electronic databases (Google Scholar, Ovid, PubMed, and Science Direct) and study selection was based on precise eligibility criteria. Random-effects meta-analyses were performed to achieve overall estimates of median survival and hazard ratios (HRs) of survival with cutoff defined lower and higher CA19-9 levels before and after surgery or chemotherapy (CT)/radiotherapy (RT) and the changes in CA19-9 levels after any treatment. A total of 41 studies (6519 patients; 42% females; age 63.3 years [95% confidence interval [CI]: 62.2, 64.4]) were included. A pooled HR of 1.79 with a narrow 95% CI (1.58, 2.01) showed that higher CA19-9 levels or less decrease in CA19-9 levels after treatment predicted shorter survival. Median survival in patients with lower and higher preoperative CA19-9 levels was 23.2 months [95% CI: 17.2, 29.2] and 14.0 months [95% CI: 10.9, 17.2], respectively, whereas median survival with lower and higher postoperative CA19-9 levels was 25.0 months [95% CI: 21.9, 28.0] and 13.0 months [95% CI: 10.9, 15.0] respectively. Median survival with lower and higher pre-CT/RT CA19-9 levels was 11.9 months [95% CI: 10.2, 13.6] and 7.7 months [95% CI: 6.2, 9.2], respectively, whereas median survival with lower and higher post-CT/RT CA19-9 levels was 15.1 months [95% CI: 13.2, 17.0] and 10.7 months [95% CI: 7.3, 14.0] respectively. A decrease in CA19-9 levels after treatment was also associated with longer survival. Thus, both pretreatment and posttreatment CA19-9 levels or their changes after treatment have good prognostic value in determining the survival of pancreatic cancer patients.