RESUMEN
We describe a 13-year-old boy with a very late presentation of vertically transmitted HIV-1 infection. The mother, an intravenous drug user before pregnancy, was diagnosed with AIDS in 1987 when the boy was 6 years old. HIV infection in her son was never suspected or investigated. No other risk factors for this infection can be attributed to the boy. On diagnosis of the infection the boy had moderately severe respiratory symptoms, as classified in category B2 of the 1994 paediatric HIV infection definition, and virological replicative kinetics and the phenotype have been determined. Standard AZT therapy has improved the clinical symptoms, with negativization of plasma p24 Ag and HIV RNA. Clinicians should be aware of this form of presentation of HIV-1 infection to avoid further delay of proper therapy.