BACKGROUND: Post-traumatic stress disorder (PTSD) is highly prevalent in children and adolescents who have experienced trauma and has high personal and health costs. Although a wide range of psychological therapies have been used in the treatment of PTSD there are no systematic reviews of these therapies in children and adolescents. OBJECTIVES: To examine the effectiveness of psychological therapies in treating children and adolescents who have been diagnosed with PTSD. SEARCH METHODS: We searched the Cochrane Depression, Anxiety and Neurosis Review Group's Specialised Register (CCDANCTR) to December 2011. The CCDANCTR includes relevant randomised controlled trials from the following bibliographic databases: CENTRAL (the Cochrane Central Register of Controlled Trials) (all years), EMBASE (1974 -), MEDLINE (1950 -) and PsycINFO (1967 -). We also checked reference lists of relevant studies and reviews. We applied no date or language restrictions. SELECTION CRITERIA: All randomised controlled trials of psychological therapies compared to a control, pharmacological therapy or other treatments in children or adolescents exposed to a traumatic event or diagnosed with PTSD. DATA COLLECTION AND ANALYSIS: Two members of the review group independently extracted data. If differences were identified, they were resolved by consensus, or referral to the review team. We calculated the odds ratio (OR) for binary outcomes, the standardised mean difference (SMD) for continuous outcomes, and 95% confidence intervals (CI) for both, using a fixed-effect model. If heterogeneity was found we used a random-effects model. MAIN RESULTS: Fourteen studies including 758 participants were included in this review. The types of trauma participants had been exposed to included sexual abuse, civil violence, natural disaster, domestic violence and motor vehicle accidents. Most participants were clients of a trauma-related support service. The psychological therapies used in these studies were cognitive behavioural therapy (CBT), exposure-based, psychodynamic, narrative, supportive counselling, and eye movement desensitisation and reprocessing (EMDR). Most compared a psychological therapy to a control group. No study compared psychological therapies to pharmacological therapies alone or as an adjunct to a psychological therapy. Across all psychological therapies, improvement was significantly better (three studies, n = 80, OR 4.21, 95% CI 1.12 to 15.85) and symptoms of PTSD (seven studies, n = 271, SMD -0.90, 95% CI -1.24 to -0.42), anxiety (three studies, n = 91, SMD -0.57, 95% CI -1.00 to -0.13) and depression (five studies, n = 156, SMD -0.74, 95% CI -1.11 to -0.36) were significantly lower within a month of completing psychological therapy compared to a control group. The psychological therapy for which there was the best evidence of effectiveness was CBT. Improvement was significantly better for up to a year following treatment (up to one month: two studies, n = 49, OR 8.64, 95% CI 2.01 to 37.14; up to one year: one study, n = 25, OR 8.00, 95% CI 1.21 to 52.69). PTSD symptom scores were also significantly lower for up to one year (up to one month: three studies, n = 98, SMD -1.34, 95% CI -1.79 to -0.89; up to one year: one study, n = 36, SMD -0.73, 95% CI -1.44 to -0.01), and depression scores were lower for up to a month (three studies, n = 98, SMD -0.80, 95% CI -1.47 to -0.13) in the CBT group compared to a control. No adverse effects were identified. No study was rated as a high risk for selection or detection bias but a minority were rated as a high risk for attrition, reporting and other bias. Most included studies were rated as an unclear risk for selection, detection and attrition bias. AUTHORS' CONCLUSIONS: There is evidence for the effectiveness of psychological therapies, particularly CBT, for treating PTSD in children and adolescents for up to a month following treatment. At this stage, there is no clear evidence for the effectiveness of one psychological therapy compared to others. There is also not enough evidence to conclude that children and adolescents with particular types of trauma are more or less likely to respond to psychological therapies than others. The findings of this review are limited by the potential for methodological biases, and the small number and generally small size of identified studies. In addition, there was evidence of substantial heterogeneity in some analyses which could not be explained by subgroup or sensitivity analyses. More evidence is required for the effectiveness of all psychological therapies more than one month after treatment. Much more evidence is needed to demonstrate the relative effectiveness of different psychological therapies or the effectiveness of psychological therapies compared to other treatments. More details are required in future trials in regards to the types of trauma that preceded the diagnosis of PTSD and whether the traumas are single event or ongoing. Future studies should also aim to identify the most valid and reliable measures of PTSD symptoms and ensure that all scores, total and sub-scores, are consistently reported.