Thirty-seven HIV-infected children have been identified in the Republic of Ireland since 1985. Only 12 (32%) of 37 were followed prospectively from birth. Median age at diagnosis was 18 months (4 weeks to 8 years). In 32 (86%) of 37 cases, HIV infection was acquired as a result of transmission from mother to infant with intravenous drug use (IVDU) the most frequent risk factor for maternal acquisition of HIV. Of these 32 children, median maternal age at delivery was 24 (interquartile range (IQR) 23-26) years with median gestation at delivery 40 (IQR 38-40) weeks. Mode of delivery was by vaginal delivery in all 29 (91%) cases where mode of delivery is known. Only 2 infants were breastfed. Seven children have died at a median age of 9 (0.8-9.6) years. As of July 1997, 12 children have AIDS, 14 have symptomatic disease without AIDS and 3 are asymptomatic. Median age at AIDS diagnosis was 2.6 (0.1-6.5) years. Median survival time post-AIDS diagnosis was 6.5 (1.8-8.3) years. Of 29 living children, 24 mothers and 14 fathers are HIV infected and only 14 children live with both parents. Childhood HIV infection has had a significant personal, social and financial impact on both Irish families and society in general. More effective measures to control HIV infection among intravenous drug users are needed. Antenatal detection of HIV-infected mothers is paramount as vertical transmission can be successfully prevented and morbidity and death can be prevented in the infected infant.