Repeated assessments of psychopathology, together with personality status, were made over two years on 181 psychiatric out-patients with generalised anxiety disorder (59), panic disorder (66), or dysthymic disorder (56) diagnosed using an interview schedule for DSM-III. Patients were randomly allocated to drug treatment, cognitive and behaviour therapy, or a self-help treatment programme. Although there were no overall differences in compliance rate and efficacy between the three modes of treatment, the psychological treatment methods, particularly self-help, were more effective in patients without personality disorder, and those with personality disorder responded better to drug treatment, primarily antidepressants. The findings suggest that assessment of personality status could be a valuable aid to selection of treatment in neurotic disorders and that self-help approaches are particularly valuable once personality disorder has been excluded.