OBJECTIVE To describe the clinical, immunologic, and psychosocial characteristics of children living with perinatally-acquired human immunodeficiency virus (HIV) infection beyond the age of 9 years. METHODS This is a descriptive cohort study of 42 surviving perinatally infected children older than 9 years followed at the Children's Hospital Acquired Immunodeficiency Syndrome (AIDS) Program (part of a university-based inner city medical center) as of June 1993. The study is based on medical record data of clinical, immunologic, and psychosocial parameters. RESULTS The cohort includes 20 boys and 22 girls with a mean age of 136 months. The mean age at diagnosis of HIV infection was 88 months, and 59.5% were asymptomatic at the time of diagnosis. Currently, after a mean follow-up period of 48 months from diagnosis, 23.8% remain asymptomatic, 19.1% have non-AIDS-defining HIV-related symptoms, and 57.1% have AIDS; 85.7% of the cohort did not develop HIV-related symptoms until after 48 months of age (late-onset prolonged survivors). There was an average annual decline of 71.4 CD4+ cells/microL in the cohort from the ages of 7 to 16 years, and 21.4% have a current CD4+ lymphocyte count of greater than 500 cells/microL, 28.6% between 200 and 500 cells/microL, and 50% less than 200 cells/microL; 76% are orphaned as a result of maternal death, with the majority of the cohort (60%) cared for by extended family members. Disclosure of diagnosis has occurred in 57.1%. The vast majority of the cohort (76%) are attending regular school, with the remainder in special education. CONCLUSIONS Although close to one quarter of the children and adolescents ages 9 to 16 years living with perinatally acquired HIV infection described in this cohort remain asymptomatic and have a relatively intact immune system, the remainder are living with significant HIV-related symptoms, many of which are chronic in nature and have an impact on daily living. The children in this cohort had both significant immunologic deterioration and symptomatic disease progression during the mean follow-up period of 48 months from the time of diagnosis with HIV infection.