The objective of this study was to define the demographic, immunologic, and clinical characteristics of children with acquired immunodeficiency syndrome (AIDS) and AIDS nephropathy, and contrast this with the existing adult data. Data from 62 pediatric patients with AIDS who were treated at SUNY Health Science Center, Brooklyn, New York, between 1983 and 1993 were analyzed. Human immunodeficiency virus (HIV) infection was acquired during the neonatal period by vertical transmission (n = 60) or blood transfusion (n = 2). All children with AIDS who exhibited clinical nephropathy died (n = 16), with mean survival of 55.3 months. In contrast, 32 of 56 AIDS patients (70%) who did not manifest nephropathy were alive at the end of the study period. Patients with nephropathy were noted to have significantly lower CD4+ lymphocyte counts than those without nephropathy. These observations suggest that the predominant renal lesion in pediatric patients who acquired HIV infection during the perinatal period is focal segmental glomerulosclerosis, although a variety of other histological lesions were present. As in adults, the survival in children is dismal following the onset of clinical renal disease. In contrast to the adult population in whom multiple risk factors can potentially contribute to AIDS-associated nephropathy, occurrence of nephropathy in children with vertical HIV transmission provides convincing evidence for the pathogenetic role of HIV infection.