Background: As the incidence and prevalence of prostate cancer continue to rise, the number of men needing help and support to assist them in coping with disease and treatment-related symptoms and their psychosocial effects is likely to increase. Objectives: To evaluate the effectiveness of psychosocial interventions for men with prostate cancer in improving quality of life (QoL), self-efficacy and knowledge and in reducing distress, uncertainty and depression. Search methods: We searched for trials using a range of electronic databases including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and PsycINFO to October 2013, together with handsearching of journals and reference lists. Selection criteria: Randomised controlled trials of psychosocial interventions for men at any stage of prostate cancer. We included psychosocial interventions that explicitly used one or a combination of the following approaches: cognitive behavioural, psychoeducational, supportive and counselling. Interventions had to be delivered or facilitated by trained or lay personnel. Data collection and analysis: Pairs of review authors independently extracted data and assessed risk of bias. We analysed data using standardised mean differences (SMDs), random-effects models and 95% confidence intervals (CIs). Main results: Nineteen studies comparing psychosocial interventions versus usual care in a total of 3204 men with prostate cancer were included in this review. All but three of these studies were conducted in the United States. Men in the psychosocial intervention group had a small, statistically significant improvement in the physical component of general health-related quality of life (GHQoL) at end of intervention (1414 participants, SMD 0.12, 95% CI 0.01 to 0.22) based on low-quality evidence. A small improvement in favour of psychosocial interventions (SMD 0.24, 95% CI 0.02 to 0.47) was also seen in the physical component of GHQoL at end of intervention for group-based interventions. No clear evidence of benefit was found for GHQoL scores at end of intervention with individual-based interventions compared with controls. Also, no clear evidence suggested that psychosocial interventions were beneficial in improving the physical component of GHQoL at four to six and at eight to 12 months post-intervention. In addition, no clear evidence showed benefit associated with psychosocial interventions for the mental component of GHQoL at end of intervention (1416 participants, SMD -0.04, 95% CI -0.15 to 0.06) based on moderate-quality evidence. Results for the mental component of GHQoL at four to six and at eight to 12 months post-intervention were compatible with benefit and harm. At end of intervention, cancer-related QoL showed a small improvement following psychosocial interventions (SMD 0.21, 95% CI 0.04 to 0.39), but at eight and 12 months, the effect was compatible with benefit and harm. For prostate cancer-specific and symptom-related QoL, the differences between groups were not significant. No clear evidence indicated that psychosocial interventions were beneficial in improving self-efficacy at end of intervention (337 participants, SMD 0.16, 95% CI -0.05 to 0.38) based on very low-quality evidence in three studies that assessed individual-based interventions. The results for self-efficacy at six to eight and at 12 months post-intervention were compatible with benefit and harm. Men in the psychosocial intervention group had a moderate increase in prostate cancer knowledge at end of intervention (506 participants, SMD 0.51, 95% CI 0.32 to 0.71) based on very low-quality evidence in two studies; this increase was also observed in the subgroups of group-based and individual-based interventions. A small increase in knowledge with psychosocial interventions was noted at three months post-intervention (SMD 0.31, 95% CI 0.04 to 0.58). The results for uncertainty (916 participants, SMD -0.05, 95% CI -0.35 to 0.26) and distress (916 participants, SMD 0.02, 95% CI -0.11 to 0.15) at end of intervention were compatible with both benefit and harm based on very low-quality evidence. No clear evidence suggests that psychosocial interventions were beneficial in reducing uncertainty and distress between groups at six to eight and at 12 months post-intervention. Finally, no clear evidence of benefit is associated with psychosocial interventions for depression at end of intervention (434 participants, SMD -0.18, 95% CI -0.51 to 0.15) based on very low-quality evidence. Individual-based interventions significantly reduced depression when compared with usual care groups. The results for depression at six and at 12 months post-intervention were compatible with benefit and harm. The overall risk of bias in the included studies was unclear or high, primarily as the result of performance bias. No data regarding stage of disease or treatment with androgen deprivation therapy (ADT) were extractable for subgroup analysis. Only one study addressed adverse effects. High attrition could indicate that some participants may not have been comfortable with the interventions. Authors' conclusions: Overall, this review shows that psychosocial interventions may have small, short-term beneficial effects on certain domains of well-being, as measured by the physical component of GHQoL and cancer-related QoL when compared with usual care. Prostate cancer knowledge was also increased. However, this review failed to demonstrate a statistically significant effect on other domains such as symptom-related QoL, self-efficacy, uncertainty, distress or depression. Moreover, when beneficial effects were observed, it remained uncertain whether the magnitude of effect was large enough to be considered clinically important. The quality of evidence for most outcomes was rated as very low according to GRADE, reflecting study limitations, loss to follow-up, study heterogeneity and small sample sizes. We were unable to perform meaningful subgroup analyses based on disease stage or treatment modality. Although some findings of this review are encouraging, they do not provide sufficiently strong evidence to permit meaningful conclusions about the effects of these interventions in men with prostate cancer. Additional well-done and transparently reported research studies are necessary to establish the role of psychosocial interventions in men with prostate cancer.