OBJECTIVE: To assess the beliefs of general practitioners (GPs), psychiatrists and clinical psychologists about the helpfulness of different interventions for mental disorders, and to examine change in beliefs over time. METHODS: A questionnaire was mailed to 6848 GPs, psychiatrists and clinical psychologists registered with Medicare Australia. The questionnaire was based around one of six vignettes describing a person with a mental disorder: depression, depression with suicidal thoughts, early schizophrenia, chronic schizophrenia, social phobia and post-traumatic stress disorder. The depression and early schizophrenia vignettes were identical to those used in a similar survey of health professionals conducted in 1996. A range of interventions were rated for their likely helpfulness for each disorder, and consensus was defined as at least 66% of each profession rating an intervention as helpful. RESULTS: Responses were received from 1536 health professionals. A broader array of interventions were endorsed for depression than in 1996, including GPs, psychiatrists, psychologists, becoming more physically active, reading about people with similar problems and how they have dealt with them, psychotherapy, and cognitive behaviour therapy. For the schizophrenia vignettes, GPs, psychiatrists and antipsychotics were thought to be helpful by a majority of professionals. A variety of professionals, psychological treatments and lifestyle activities were endorsed for the anxiety disorders. Differences between professions were noted in beliefs about the helpfulness of antidepressants and counsellors for anxiety disorders and depression, as well as cognitive behaviour therapy for schizophrenia. CONCLUSION: Consensus across professions was reached on the helpfulness of a variety of interventions for each mental disorder, although there were some notable differences in beliefs. The study gives an updated overview of treatment beliefs for mental disorders by Australian health professionals, which can be used as a benchmark with which to compare the beliefs of the Australian public.