A meta-analysis was conducted to estimate the prevalence of posttraumatic stress disorder (PTSD) among peacekeepers. A systematic review was carried out using Medline, Institute for Scientific Information/Web of Science and Published International Literature on Traumatic Stress databases, leading to a total of 12 studies reporting PTSD estimates. Pooled current PTSD prevalence was 5.3%, ranging from 0.05% to 25.8%, and a metaregression was used to investigate the variables that could account for the lack of homogeneity. However, none of the extracted information was capable of explaining the heterogeneity of the estimates. Peacekeeping studies presented different methodologies such as several screening instruments and different times from the deployment to the moment of PTSD assessment. The wide difference found among those estimates highlights the importance of the creation of standards for PTSD evaluation among peacekeepers.