OBJECTIVE: To assess the effectiveness of teaching general practitioners skills in brief cognitive behaviour therapy. DESIGN: Parallel group, cluster randomised, controlled trial of an educational package on cognitive behaviour therapy. SETTING: General practices in north London. PARTICIPANTS: 84 general practitioner principals and 272 patients attending their practices who scored above the threshold for psychological distress on the hospital anxiety and depression scale. Intervention: A training package of four half days on brief cognitive behaviour therapy. Main outcome measures: Scores on the depression attitude questionnaire (general practitioners) and the Beck depression inventory (patients). RESULTS: Doctors' knowledge of depression and attitudes towards its treatment showed no major difference between intervention and control groups after 6 months. The training had no discernible impact on patients' outcomes. CONCLUSION: General practitioners may require more training and support than a basic educational package on brief cognitive behaviour therapy to acquire skills to help patients with depression.