The issue of whether outpatient treatment of alcoholism is cost-advantageous, in the long run, for health maintenance organizations (HMOs) depends in part on whether alcoholics represent a relatively heavy burden on the health care delivery system. To clarify this issue, the paper asks whether alcoholics utilize HMO services at higher rates and in different ways than do other HMO members, and whether alcoholics experience more illnesses and injuries associated with their service utilization. The study subjects were alcoholics, identified during one year as new clients of an HMO's counseling department, which houses an alcoholism treatment component. Study subjects were matched with controls on the basis of sex, age, date of HMO enrollment, type of membership and family size. HMO medical records provided data on service utilization and associated morbidities during the three-year study period. Alcoholics were found to have utilized about 50 per cent more of all HMO services studied than did their matched controls. Alcoholics were especially high utilizers of more expensive, inpatient services. Psychosocial problems and problems classified as accidents, poisonings and violence were much more likely to underlie alcoholics' hospitalizations, and, to a lesser extent, their outpatient noncounseling utilization, than was the case for controls. Some tendency was noted for more chronic illnesses to be associated with alcoholics' service utilization, and more acute illnesses with controls' utilization.