OBJECTIVE: To conduct a feasibility and efficacy trial of mindfulness therapy in somatization disorder and functional somatic syndromes such as fibromyalgia, irritable bowel syndrome, and chronic fatigue syndrome, defined as bodily distress syndrome (BDS). METHODS: We randomized 119 patients to either mindfulness therapy (mindfulness-based stress reduction and some cognitive behavioral therapy elements for BDS) or to enhanced treatment as usual (2-hour specialist medical care and brief cognitive behavioral therapy for BDS). The primary outcome measure was change in physical health (SF-36 Physical Component Summary) from baseline to 15-month follow-up. RESULTS: The study is negative as we could not demonstrate a different development over time for the two groups (F(3,2674)=1.51, P=.21). However, in the mindfulness therapy group, improvement was obtained toward the end of treatment and it remained present at the 15-month follow-up, whereas the enhanced treatment as usual group achieved no significant change until 15-month follow-up. The change scores averaged half a standard deviation which amounts to a clinically significant change, 29% changed more than 1 standard deviation. Significant between-group differences were observed at treatment cessation. CONCLUSION: Mindfulness therapy is a feasible and acceptable treatment. The study showed that mindfulness therapy was comparable to enhanced treatment as usual in improving quality of life and symptoms. Nevertheless, considering the more rapid improvement following mindfulness, mindfulness therapy may be a potentially useful intervention in BDS patients. Clinically important changes that seem to be comparable to a CBT treatment approach were obtained. Further research is needed to replicate or even expand these findings.