A cross-sectional survey to assess the impact of the paediatric HIV/AIDS epidemic on the hospital-based health care system was performed in state-financed hospitals in Catalonia during 1992, raising issues of relevance today. Out of the 27 hospitals contacted, 20 responded. A considerable proportion of the health care to children with an HIV-related condition was provided by four hospitals. The average length of stay of the 176 HIV patients who were admitted was 10.8 days; these patients were admitted to the hospital twice a year on average. Nearly half of the out-patients who attended with an HIV-related condition were either seropositive without a confirmed diagnosis of an HIV infection (class P-0) or seronegative. Thirteen per cent of the overall admissions to paediatric day care hospitals were attributable to an HIV-related condition. By ownership status of the hospitals, HIV/AIDS paediatric in-patients of public hospitals generated the majority of admissions per patient per year, and had the shortest lengths of stay. Unlike the HIV/AIDS epidemic in adults, the magnitude and characteristics of the epidemic in children may not require the shift of hospital-based health care to primary health care.