Background: : Evidence for the efficacy of treatments for post-traumatic stress disorder (PTSD) is urgently required. This systematic review and meta-analysis examines the efficacy of interpersonal psychotherapy (IPT) in reducing the symptoms of PTSD. Methods: : Five databases were searched from inception until November 2018 to identify randomized controlled trials (RCTs) that assessed the efficacy of IPT in patients with PTSD symptoms. The reference lists of included studies were also hand searched. A random effects model was used to estimate changes in a clinician-administered PTSD scale, or self-reported symptoms. Results: : Of 509 screened abstracts, ten clinical trials (11 study arms) involving 755 patients with PTSD symptoms were included. Nine studies (10 study arms) were included in the meta-analysis. The overall standardized mean difference was -0.44 (CI: -0.69, -0.19), p = 0.0005. This represents a change in the clinically administrated PTSD Scale (CAPS) of approximately 12 points. IPT was not superior to other active controls, such as medication and non-IPT psychotherapies, but was significantly superior to passive controls, such as waiting list and educational pamphlets. Limitations: : Most studies modified the IPT protocol and did not comprehensively assess clinician fidelity to the protocol. The included studies generally had small sample sizes and were of limited quality. Conclusions: : IPT may be an effective treatment for PTSD, but clinical trials with larger sample sizes and improved methodology are required to confirm effects.