BACKGROUND: Recently, mindfulness-based therapies have emerged as a treatment modality for OCD, but there is sparse controlled data. We report the efficacy of mindfulness-based cognitive therapy (MBCT) in treating OCD in comparison with stress management training (SMT). METHODS: 60 outpatients with DSM-IV-TR OCD attending a specialty OCD clinic were randomly assigned in 1:1 ratio to either MBCT (n=30) or SMT (n= 30). Both the groups received 12 weekly sessions of assigned intervention. An independent blind rater assessed the primary outcome measure at baseline and at the end of 12 weeks. RESULTS: Significantly greater proportion of patients responded to MBCT than to SMT (80% vs. 27%, P <0.001). In the linear mixed-effects modelling for intent-to-treat analysis, there was a significant reduction in the illness severity measured using the Yale-Brown Obsessive-Compulsive Scale, obsessive beliefs of 'responsibility/threat estimation' and 'perfectionism/intolerance of uncertainty' measured using the Obsessive Beliefs Questionnaire and anxiety. LIMITATIONS: Small sample size with a relatively high attrition in the control group. Lack of a cognitive behaviour therapy (CBT) control group. CONCLUSIONS: Mindfulness-based cognitive therapy is efficacious in the treatment of OCD. Future studies should compare MBCT with CBT in larger representative samples and also examine the sustainability of change in longitudinal studies.