Among 178 HIV-infected men from the San Francisco City Clinic Cohort (SFCCC), we examined the association between health insurance and use of outpatient services and treatment. For men with private insurance, we also assessed the frequency of avoiding the use of health insurance. Men without private insurance reported fewer outpatient visits than men with fee-for-service or managed-care plans. Use of zidovudine for eligible men was similar for those with fee-for-service plans (74%), managed-care plans (77%), or no insurance (61%). Use ofPneumocystis cariniipneumonia prophylaxis was similar for those with fee-for-service (93%) and managed-care plans (83%) but lower for those with no insurance (63%). Of 149 men with private insurance, 31 (21%) reported that they had avoided using their health insurance for medical expenses in the previous year. In multivariate analysis, the independent predictors of avoiding the use of insurance were working for a small company and living outside the San Francisco Bay Area. Having private insurance resulted in higher use of outpatient services, but the type of private insurance did not appear to affect the use of service or treatment. Fears of loss of coverage and confidentiality may negate some benefits of health insurance for HIV-infected persons.