Peripheral blood and bone marrow findings are presented for six homosexual males with Kaposi's sarcoma. Cytopenia in one or more cell lines was common in this group of patients, including two individuals with pancytopenia. Bone marrow findings in all patients, while not specific, were similar in that adequate numbers of normal appearing erythroid, myeloid, and megakaryocytic elements were present. Mild plasmacytosis as well as reticulin fiber increase were common findings. No patient, at time of study, demonstrated marrow involvement with Kaposi's sarcoma. We conclude that depression of peripheral blood counts in these patients was not due to marrow underproduction, and discuss possible mechanisms for increased blood cell destruction.