ABSTRACT. Objective: Studies of alcohol brief intervention for medical inpatients have mixed results. We explored potential moderators of the effectiveness of brief intervention for unhealthy alcohol use among medical inpatients. Method: This is a secondary analysis of a randomized controlled trial of brief motivational counseling among 341 urban-hospital medical inpatients (99 women) with unhealthy alcohol use. Self-reported main outcomes were receipt of alcohol treatment by 3 months in subjects with dependence and change in the mean number of drinks per day 3 and 12 months after enrollment in all subjects. Results: Among subjects with dependence, the effect of brief intervention on receipt of alcohol treatment differed signifi cantly by gender and age (p = .02 for each interaction). In stratifi ed analyses, brief intervention was associated with receipt of alcohol treatment in women (adjusted odds ratio [AOR] = 3.9, 95% confi dence interval [CI]: 1.2-12.7), and younger (<44 years) subjects (AOR = 3.6, 95% CI: 1.3-10.1). Among subjects with nondependent, unhealthy alcohol use, brief intervention was signifi cantly associated with fewer drinks per day and better physical health-related quality of life at 3 months. However, among those with dependence, intervention was associated with worse physical health-related quality of life and more hospital use, and no changes in drinking. In adjusted analyses among those with and without dependence, brief intervention was not associated with mental health-related quality of life, alcohol problems, or readiness to change. Effects of brief intervention on consumption outcomes were not consistently moderated by demographic characteristics, comorbidity/health, or readiness to change. Conclusions: Some medical inpatients with unhealthy alcohol use, particularly women, younger adults, and patients without dependence may benefi t from brief intervention. Few factors that were expected to moderate brief intervention effects did so. Additional research should assess which medical inpatients, if any, can benefi t from brief intervention. (J. Stud. Alcohol Drugs 70: [426][427][428][429][430][431][432][433][434][435] 2009)