BACKGROUND:Individual-based cognitive-behavioural therapy (CBT) is in short supply and expensive. AIMS: The aim of this randomised controlled trial (RCT) was to compare mindfulness-based group therapy with treatment as usual (primarily individual-based CBT) in primary care patients with depressive, anxiety or stress and adjustment disorders. METHOD: This 8-week RCT (ClinicalTrials.gov ID: NCT01476371) was conducted during spring 2012 at 16 general practices in Southern Sweden. Eligible patients (aged 20-64 years) scored ≥10 on the Patient Health Questionnaire-9, ≥7 on the Hospital Anxiety and Depression Scale or 13-34 on the Montgomery-Åsberg Depression Rating Scale (self-rated version). The power calculations were based on non-inferiority. In total, 215 patients were randomised. Ordinal mixed models were used for the analysis. RESULTS: For all scales and in both groups, the scores decreased significantly. There were no significant differences between the mindfulness and control groups. CONCLUSIONS: Mindfulness-based group therapy was non-inferior to treatment as usual for patients with depressive, anxiety or stress and adjustment disorders.