OBJECTIVE: Mindfulness-based cognitive therapy (MBCT) is a programme developed to prevent depression relapse, but has been applied for other disorders. Our objective was to systematically review and meta-analyse the evidence on the effectiveness and safety of MBCT for the treatment of mental disorders. METHODS: Searches were completed in CENTRAL, MEDLINE, EMBASE, LILACS, PsychINFO, and PsycEXTRA in March 2011 using a search strategy with the terms 'mindfulness-based cognitive therapy', 'mindfulness', and 'randomised controlled trials' without time restrictions. Selection criteria of having a randomised controlled trial design, including patients diagnosed with mental disorders, using MBCT according to the authors who developed MBCT and providing outcomes that included changes in mental health were used to assess 608 reports. Two reviewers applied the pre-determined selection criteria and extracted the data into structured tables. Meta-analyses and sensitivity analyses were completed. RESULTS: Eleven studies were included. Most of them evaluated depression and compared additive MBCT against usual treatment. After 1 year of follow-up MBCT reduced the rate of relapse in patients with three or more previous episodes of depression by 40% (5 studies, relative risk [95% confidence interval]: 0.61 [0.48, 0.79]). Other meta-analysed outcomes were depression and anxiety, both with significant results but unstable in sensitivity analyses. Methodological quality of the reports was moderate. CONCLUSION: Based on this review and meta-analyses, MBCT is an effective intervention for patients with three or more previous episodes of major depression.