Environmental and genetic factors contribute to the development of posttraumatic stress disorder (PTSD). Variation in the 5‐HTTLPR polymorphism of the serotonin transporter gene has been hypothesized to affect risk for PTSD. With the aim of investigating this association, we conducted a meta‐analysis to shed light on prior controversial results and increase statistical power to detect smaller effect sizes. PubMed and ISI databases were searched for studies published until December 2012. Twelve studies have been included, all based on trauma‐exposed samples. Data were analyzed with Cochrane Collaboration Review Manager Software (Version 5). Quality and publication bias were assessed. Metaregressions were performed using Comprehensive Meta‐Analysis software, Version 2. Taking into account all studies, no association was found between 5‐HTTLPR and PTSD (p = .10), with evidence of between‐study heterogeneity, which could be partly explained by gender differences. In sensitivity analyses, we found an association between SS genotype and PTSD in high trauma‐exposed participants (p < .001). To be a carrier of the SS genotype seems to represent a risk factor for PTSD in high trauma exposure. Further studies focusing on Gene × Environment interactions are needed to better understand the role of this polymorphism in PTSD.