BACKGROUND Alcoholism is a common disorder that often results in increased use of medical services. Research describing alcoholism among both outpatients and ethnic minorities has been sparse. METHODS In this study, the Short Michigan Alcoholism Screening Test was used as part of a health screening interview of patients attending a South Texas family health clinic. Screening was used to detect alcoholism and identify the health care needs in this predominantly Mexican American population. RESULTS Consistent with other studies, alcoholism was more prevalent among men than among women. The prevalence of 24.4% among Mexican American men was similar to that among men from other ethnic backgrounds. The 4.2% prevalence among Mexican American women was comparable to that among other women. Equal percentages of alcoholics were identified in the primary care clinic and the "walk-in" clinic. Compared with nonalcoholic patients, alcoholic patients were more often unemployed or disabled, and reported more hospitalizations during the previous year. CONCLUSIONS These findings suggest that alcoholism is as prevalent and costly a disease among Mexican Americans as it is in other ethnic groups in our society. Alcoholism can readily be detected in a variety of outpatient settings when screening is used. Employment status might serve as an indicator for alcoholism screening, but ethnicity did not. Research into socio-economic and cultural influences on alcoholism may improve the effectiveness of diagnosis and treatment of this prevalent disease.