Posttraumatic stress disorder (PTSD) is a prevalent and disabling mental illness. Small studies found atypical antipsychotics (AAs) to be beneficial in the treatment of patients with PTSD regardless of psychotic symptoms who are unresponsive to conventional pharmacological treatments such as serotonin selective reuptake inhibitors. This study reports the results of a meta-analysis of existing randomized, double-blind, placebo-controlled clinical trials (RCTs) of AAs as a monotherapy or augmentation therapy for the treatment of patients with PTSD. Seven RCTs were identified through extensive scans of databases, which included PubMed, MedLine, the National PTSD Center Pilots database, PsycINFO, Cochrane Central Register of Controlled Trials, and the Abstracts Library of the American Psychiatric Association with predefined inclusion criteria. Dichotomous and continuous measures were performed using a fixed effects model, heterogeneity was assessed, and subgroup analyses were done. Data from seven RCTs involving a total of 192 PTSD patients (102 randomized to AAs and 90 randomized to placebo) were analyzed. The results show that AAs may have a beneficial effect in the treatment of PTSD, as indicated by the changes from baseline in Clinician Administered PTSD Scale total scores [standardized mean difference (SMD)=-0.45, 95% confidence interval (CI) (-0.75, -0.14), P=0.004]. In addition, the overall SMD of the mean changes in the three Clinician Administered PTSD Scale subscores was statistically significant (P=0.007) between AAs and placebo groups, favoring AAs over placebo (SMD=-0.27, 95% CI=-0.47, -0.07). In particular, the symptom of 'intrusion' was mainly responsible for this significance. Clinical significance of the results, however, should be carefully interpreted and translated into clinical practice, given that the quality and availability of currently existing RCTs included in the analysis.