Kaposi's sarcoma involvement of the bone marrow. Kaposi's sarcoma (KS) is a predominantly cutaneous malignancy with several clinical variants. Extracutaneous sites of involvement are uncommon in all disease variants except epidemic KS (human immunodeficiency virus related) and the African lymphadenopathic variant. Extracutaneous KS usually involves the lymph nodes, gastrointestinal tract, and respiratory tract. The authors report the first description of a patient with classic KS to have bone marrow involvement. Two additional patients with KS variants and bone marrow involvement have been described. Bone marrow tumor invasion should be considered in patients with KS and hematologic abnormalities. 