Children born to human immunodeficiency virus (HIV)-infected mothers often do not live with a biologic parent because of drug use, illness, or death of the mother. Public health officials need to know the number and proportion of children who will require care by someone other than a biologic parent (alternative care giver). The Pediatric Spectrum of Disease project, conducted in six different geographic regions in the United States, assesses issues specific to HIV in children. Among the information being collected in this study are data regarding the primary care giver. Of 1683 children born to HIV-infected mothers and enrolled through 1990, 55% (937) were living with a biologic parent, 10% (169) with another relative, 28% (455) were in foster care, 3% (55) had been adopted, and 4% (67) lived in group settings or with other care givers. In all locations and for all racial/ethnic groups, children of mothers who used intravenous drugs were more likely to be living with an alternative care giver than were children of mothers who had not used intravenous drugs (odds ratio 4.15). However, there were striking variations by study location (odds ratio range 1.4 to 7.2). The data suggest that maternal drug use may be the most important factor determining whether a child lives with a biologic parent and that there are also regional differences in alternative care placement.