The life expectancy of children with human immunodeficiency virus (HIV) infection acquired through mother-to-child transmission has important clinical and public health significance. Several sources of population-based surveillance data from New York City, covering 1982 through the end of 1994, were combined to estimate long-term survival of HIV-infected children and age-specific prevalence. HIV incidence among newborns was estimated by applying expected transmission rates to seroprevalence surveys of parturient women and by using back-calculation methods. HIV prevalence in childhood was based on cumulative HIV incidence and cumulative mortality, adjusting for underreporting of death and background causes of death. A modified actuarial method was developed to estimate survival of infected children. At the beginning of 1995, between 1,945 and 3,323 children less than age 13 years were estimated to be living with HIV infection acquired through mother-to-child transmission in New York City. Between 36% and 61% of these infected children were estimated to survive to age 13 years (median survival, 8.6 years to >13 years). A substantial proportion of infected children will survive to adolescence. Thus, it is important that their educational, medical, and other needs be considered. These methods may be useful in other areas in which HIV seroprevalence data among childbearing women and HIV mortality statistics are available.