OBJECTIVE: Posttraumatic stress disorder (PTSD) is an important mental health issue in terms of the number of people affected and the morbidity and functional impairment associated with the disorder. The purpose of this study was to examine the efficacy of all treatments for PTSD. DATA SOURCES: PubMed, MEDLINE, PILOTS, and PsycINFO databases were searched for randomized controlled clinical trials of any treatment for PTSD in adults published between January 1, 1980, and April 1, 2012, and written in the English language. The following search terms were used: post-traumatic stress disorders, posttraumatic stress disorder, PTSD, combat disorders, and stress disorders, post-traumatic. STUDY SELECTION: Articles selected were those in which all subjects were adults with a diagnosis of PTSD based on DSM criteria and a valid PTSD symptom measure was reported. Other study characteristics were systematically collected. The sample consisted of 137 treatment comparisons drawn from 112 studies. RESULTS: Effective psychotherapies included cognitive therapy, exposure therapy, and eye movement desensitization and reprocessing (g = 1.63, 1.08, and 1.01, respectively). Effective pharmacotherapies included paroxetine, sertraline, fluoxetine, risperidone, topiramate, and venlafaxine (g = 0.74, 0.41, 0.43, 0.41, 1.20, and 0.48, respectively). For both psychotherapy and medication, studies with more women had larger effects and studies with more veterans had smaller effects. Psychotherapy studies with wait-list controls had larger effects than studies with active control comparisons. CONCLUSIONS: Our findings suggest that patients and providers have a variety of options for choosing an effective treatment for PTSD. Substantial differences in study design and study participant characteristics make identification of a single best treatment difficult. Not all medications or psychotherapies are effective.