Human immunodeficiency virus type 2 infection is rare in children. This virus can be acquired through transfusion and also by the maternofetal route, especially when the mother becomes infected during pregnancy. Diagnosis based on specific serologic tests is simple after the age of 18 months. In the perinatal period, however, viral isolation by culture or polymerase chain reaction DNA amplification or both appears to be less sensitive than in the case of human immunodeficiency virus type 1. Disease progression is far slower than with human immunodeficiency virus type 1, but severe immunodeficiency can occur.