The aim of this pilot study was to examine the effectiveness of an intensive form of cognitive behavioural group treatment practised routinely in a psychiatric clinic. A total of 27 outpatients with social phobia of long duration were assigned to a 41-hour treatment administered over 2 periods of 3.5 and 4.5 days, 1 week apart. Four groups, each comprising 6-8 patients, participated in the study. All except 1 patient (26/27) completed the treatment and 20 patients participated in all follow-up sessions after 3, 6 and 12 months. Treatment significantly reduced fear and avoidance of social interaction and performance, anticipatory anxiety and symptoms' influence on daily life. Follow-up assessments indicated maintained or increased improvement from post-test to 1 year and large sensitivity to treatment at both post-test and 1 year. Of the patients in the study, 85% were taking a prescribed drug, and 70% had taken medication for at least 1 year before they entered the treatment. At 1-year follow-up 52% had discontinued medication.