This study's analysis addresses trends in hospital utilization and costs for patients with human immunodeficiency virus acquired immunodeficiency syndrome (HIV/AIDS) from 1994 through 1996 in South Carolina, as well as the effect of patient sociodemographics, referrals, and provider characteristics. This is a population-based study of all emergency department visits and hospitalizations occurring during that time period. The total hospital charge per patient significantly increases over time, while the total inpatient days per patient decreases significantly, and the charge per day increases significantly. The proportion of patients with public insurance or who are indigent is increasing, and the proportion of those with private insurance is decreasing. Other variables that have a significant impact on total hospital charges, total inpatient days, and charges per day are types of insurance, physicians specialty, discharge status, and number of diagnoses (severity). Persons who are Medicare eligible are sicker and have higher hospital costs and more inpatient days when compared to those with Medicaid. Intensity of services (hospital charges per day) is associated with private insurance and self-pay patients. Persons with terminal illness stay longer and have higher costs. When HIV/AIDS is the primary admitting diagnosis, there are higher hospitalization costs. Increasing severity of illness (number of diagnoses) leads to higher total hospital charges and days. With the introduction of new AIDS treatments in 1996, further study is required to determine the effects of new drugs, physician specialties, and other provider characteristics on the cost and utilization of health care services, both inpatient and outpatient.