Live virus vaccines can cause serious adverse reactions when administered to immunocompromised patients. Because children infected with human immunodeficiency virus (HIV) may be immunosuppressed, immunization of these children with live virus vaccines is a potential problem. A retrospective survey was conducted by the New York City Department of Health, with consultation from the Centers for Disease Control, to evaluate the frequency of serious adverse events following receipt of live vaccines among children with HIV infection receiving pediatric care in New York City and New Jersey. Outpatient records of 319 children being cared for by 16 participating physicians were reviewed. Of the 319 charts, 221 (69%) contained vaccination histories. Perinatal transmission of HIV infection was suspected for 208 (94%) of the 221 cases and infection via transfusion for the remaining 13 (6%). Of the 221 for whom immunization histories were available, 180 (81%) had received at least one dose of live oral polio vaccine and 70 (32%) had received measles, mumps, and rubella vaccine. There were 120 children for whom a temporal relationship between immunization and onset of symptoms of immunodeficiency could be seen; 46/120 had received at least one dose of oral polio vaccine and 23/45 had received measles, mumps, and rubella vaccine after onset of symptoms. Although follow-up of this population has been limited, there were no reports of serious adverse events such as typical or atypical measles, paralytic poliomyelitis, or aseptic meningitis in the month following vaccination.(ABSTRACT TRUNCATED AT 250 WORDS)