A three-year-old-boy with generalized Kaposi's sarcoma (KS) is presented. The child died of progressive pulmonary insufficiency on the eighteenth day of the course of his illness, the tenth hospital day. On postmortem examination diffuse KS infiltration was observed in the respiratory and gastrointestinal tracts, lymph nodes, liver, spleen and thymus. The patient was considered to be a case of KS unrelated to AIDS because of his negative HTLV-III antibody and epidemiologic characteristics, and therefore was believed to have primary aggressive KS.