Over an 18-month period (January 1987 to June 1988), Group Health Cooperative (GHC) examined the direct medical costs and service utilization of enrollees with Class IV HIV conditions. Data is presented on inpatient stays, outpatient visits by specialty, and outpatient pharmacy, laboratory, home health, and purchased-outside services. Results for enrollees with Class IV HIV disease are compared to those for a control sample of enrollees, age and sex matched with the HIV sample. The per member per month (PMPM) cost for the HIV sample was $1,761, approximately 33 times greater than the PMPM cost for the control sample. Group Health's annualized cost of $21,130 per case and diagnosis-to-death cost of $31,700-$42,300 per case are comparable to costs of Class IV care in other settings. Primary care costs were 11 times that of controls. Several specialty areas (e.g., infectious disease, pulmonary, oncology, and radiation therapy) were impacted to a greater extent.