The objective of this study was to evaluate the 6-month outcomes of a brief intervention to reduce alcohol consumption by psychiatric in-patients in the general hospital setting and following resolution of psychiatric morbidity. Patients from the psychiatric wards of three general hospitals were screened using the Alcohol Use Disorders Identification Test. Of 144 people approached who matched the study criteria, 120 (83%) people aged 18-64 years (mean 31.7) were recruited. Participants were randomized to either a brief motivational interview or an information package to reduce alcohol consumption. Alcohol consumption was assessed as total weekly consumption and categorized on Australian National Health and Medical Research Council (NH&MRC) criteria. We delivered 62 motivational interviews and 58 information packages. At the 6-month follow-up 83 (69%), participants were reassessed. Both groups had significantly reduced alcohol consumption. However, the motivation group had a significantly greater reduction in weekly consumption than the information group (F = 6.8, (1,65) p < 0.025) after controlling for age, sex, SCL-90-R GSI and alcohol dependence (and baseline alcohol consumption). A greater proportion of the motivation group compared to the information group also 'improved' in their classification on NH&MRC criteria (chi(2) = 7.3, df 1, p < 0.01). Brief interventions, especially motivational interviews, are effective in reducing alcohol use in persons with psychiatric disorders. They are effective across the mid-range of GSI severity scores for in-patients. Screening and brief interventions can and should be incorporated into the routine assessment and management in psychiatric units.