Background. Cognitive-behavioural therapy (CBT) brings about significant clinical improvement in anxiety and depression, but therapists are in short supply. We report the first phase of a randomized controlled trial of an interactive multimedia program of cognitive-behavioural techniques, Beating the Blues™ (BtB), in the treatment of patients in general practice with anxiety, depression or mixed anxiety/depression. Method. One hundred and sixty-seven adults suffering from anxiety and/or depression and not receiving any form of psychological treatment or counselling were randomly allocated to receive, with or without medication, BtB or treatment as usual (TAU). Measures were taken on five occasions: prior to treatment, 2 months later, and at 1, 3 and 6 months follow-up using the Beck Depression Inventory, Beck Anxiety Inventory and Work and Social Adjustment Scale. Results. Patients who received BtB showed significantly greater improvement in depression and anxiety compared to TAU by the end of treatment (2 months) and to 6 months follow-up. Symptom reduction was paralleled by improvement in work and social adjustment. There were no interactions of BtB with concomitant pharmacotherapy or duration of illness, but evidence, on the Beck Anxiety Inventory only, of interaction with primary care practice. Importantly, there was no interaction between the effects of BtB and baseline severity of depression, from which we conclude that the effects of the computer program are independent of starting level of depression. Conclusions. These results demonstrate that computerized interactive multimedia cognitive-behavioural techniques under minimal clinical supervision can bring about improvements in depression and anxiety, as well as in work and social adjustment, with and without pharmacotherapy and in patients with pre-treatment illness of durations greater or less than 6 months. Thus, our results indicate that wider dissemination of cognitive-behavioural techniques is possible for patients suffering from anxiety and/or depression.