Fourteen infants with clinical and laboratory features of an acquired immunodeficiency syndrome were identified in a single metropolitan area from November 1980 to July 1983. Patients were predominantly of Haitian parentage, although two cases occurred in offspring of non-Haitian intravenous drug abusers. Only one patient had received a blood transfusion before the development of clinical findings. The predominant clinical findings included failure to thrive, persistent infection of the oral mucosa by Candida albicans, chronic pulmonary infiltrates, hepatosplenomegaly, lymphadenopathy, and diarrhea. Immunologic studies showed most of the infants to have inverted ratios of T-cell subsets, greatly increased immunoglobulin levels, and circulating immune complexes. Lymphopenia was not common, as it is in adult patients. Infectious agents responsible for opportunistic infections in this series included Pneumocystis carinii, herpesviruses, particularly cytomegalovirus, and C. albicans. Bacterial infections were common, and gram-negative sepsis was the major cause of death in the seven infants who have died. At autopsy, two infants had disseminated lymphadenopathic Kaposi's sarcoma. These observations suggest the likelihood of transplacental, perinatal, or postnatal transmission of an as yet unidentified infectious agent that causes this disease.