OBJECTIVE The purpose of this research was to describe hospital use patterns of HIV-infected children in the United States. METHODS We analyzed a nationwide, stratified probability sample of 2.5 million hospital discharges of children and adolescents during the year 2000, weighted to 7.3 million discharges nationally. We excluded discharges after hospitalizations related to pregnancy/childbirth and their complications and discharges of neonates <1 month of age and of patients >18 years of age. Diagnoses were identified through the use of the Clinical Classification Software with grouping of related diagnoses. RESULTS We estimated that there were 4107 hospitalizations of HIV-infected children in 2000 and that these hospitalizations accounted for approximately dollar 100 million in hospital charges and >30000 hospital days. Infections, including sepsis and pneumonia, were among the most frequent diagnoses in such hospitalizations, followed by diagnoses related to gastrointestinal conditions, nutritional deficiencies and anemia, fluid/electrolyte disorders, central nervous system disorders, cardiovascular disorders, and respiratory illnesses. Compared with hospitalizations of non-HIV-infected children, hospitalizations of HIV-infected ones were more likely to be in urban areas, in pediatric/teaching hospitals, and in the Northeast, and the expected payer was more likely to be Medicaid (77.6% vs 37.2%). Compared with children without HIV, those with HIV tended to be older (median age: 9.5 years vs 5.2 years), to have been hospitalized longer (mean: 7.8 days vs 3.9 days), and to have incurred higher hospital costs (mean: dollar 23221 vs dollar 11215); HIV-associated hospitalizations ended in the patient's death more frequently than non-HIV ones (1.8% vs 0.4%), and complications of medical care were also more common (10.8% vs 6.2%). CONCLUSIONS Infections account for the majority of hospitalizations of HIV-infected children in the United States, although nutritional deficiencies, anemia and other hematologic disorders, gastrointestinal and renal disorders, and complications of medical care are also more common among hospitalized children with HIV than among those without HIV.