Background.Previous research has indicated that the needs of persons infected with human immunodeficiency virus (HIV) for supportive services often go unmet. Although case management has been advocated as a method of decreasing unmet needs for supportive services, its effectiveness is poorly understood.Objectives.To assess the prevalence of need and unmet need for supportive services and the impact of case managers on unmet need among HIV-infected persons.Research Design.National probability sample.Participants.A total of 2,832 HIV-infected adults receiving care.Measures.Need and unmet need for benefits advocacy, housing, home health, emotional counseling, and substance abuse treatment services.Results.Sixty-seven percent of the sample had a need for at least one supportive service, and 26.6% had an unmet need for at least one service in the previous 6 months. Contingent unmet need (unmet need among persons who needed the service) was greatest for benefits advocacy (34.6%) and substance abuse treatment (27.6%). Fifty-seven percent of the sample had had contact with their case manager in the previous 6 months. In multiple logistic regression analysis, with adjustment for covariates, having a case manager was associated with decreased unmet need for home health care (OR = 0.39; 95% CI = 0.25-0.60), emotional counseling (OR = 0.54; 95% CI = 0.38-0.78), and any unmet need (OR = 0.70; 95% CI = 0.54-0.91). An increased number of contacts with a case manager was significantly associated with lower unmet need for home health care, emotional counseling, and any unmet need.Conclusions.Need and unmet need for supportive services among HIV-infected persons is high. Case management programs appear to lower unmet need for supportive services.