Human immunodeficiency virus infection is specific in children and related to their immune system. Recurrent bacterial and viral infections precede opportunistic infections. They are associated with non-specific manifestations (e.g. lymphadenopathy) and frequently reveal the HIV infection. Acute or chronic interstitial pneumonia is the main cause of morbidity and mortality (two-thirds of the cases); 34 to 90 p. 100 of children have neurological but also gastrointestinal and haematological involvement. All organs and systems can be directly or indirectly affected by the virus with immune and infectious consequences. The prognosis is very poor with an actuarial survival rate of 60 p. 100 at 5 years, so that strict clinical and laboratory monitoring is mandatory.