BACKGROUND: Hazardous alcohol use is associated with an increased risk for development of a substance use disorder, leading to negative outcomes in psychiatric patients. AIMS: In order to investigate whether psychiatric outpatients' hazardous alcohol consumption could be reduced by way of a brief intervention by telephone. METHOD: Non-psychotic psychiatric outpatients, n = 1,670, completed a self-rating form concerning alcohol habits (AUDIT). Participants with scores indicating risk consumption (n = 344) were randomised to intervention (immediate advice) or control (advice after 6 months). RESULTS: Hazardous alcohol habits occurred among 19% of the women and 24% of the men. In the intervention group, half of the patients reduced their alcohol consumption to non-hazardous levels at 6-month follow-up (ITT analysis). In women, 41.5% in the intervention group had no hazardous consumption at follow-up compared to 24.7% in the control group (P = 0.003), corresponding figure for men was 49.1 and 34.0%. CONCLUSION: Brief intervention seems to be effective to reduce hazardous alcohol consumption in psychiatric outpatients.