We present a child with human immune deficiency virus-1 infection associated with a multiple sclerosis-like illness. This case is the first reported of human immune deficiency virus-1 infection and a disease indistinguishable from multiple sclerosis in a child. Because of the rarity of either disease in pediatric patients, their coexistence in a child argues in favor of a casual association between the two illnesses, thus reinforcing the long-held assumption that viral agents may trigger some of the immunologic abnormalities underlying multiple sclerosis. Cases in which such an association was present in adults are also described in this article.