We compared bone marrow findings in 2 groups of patients with AIDS during 2 different periods: group 1, n = 20; male/female ratio, 19/1; and group 2, n = 120; male/female ratio, 6/1. Bone marrow iron stores were decreased significantly in group 2 (P < .01), and the incidence of AIDS-related lymphomas was higher, with frequent bone marrow involvement. Two group 1 patients had Kaposi sarcoma, and a 21-month-old girl with transfusion-transmitted AIDS had Burkitt-like lymphoma. In group 2, 44 patients had a history of malignant neoplasms, including Kaposi sarcoma (10 cases), hematologic neoplasms (33 cases), and metastatic leiomyosarcoma (1 case). Of the 120 patients, 15 (12.5%) had bone marrow involvement by malignant neoplasms. The majority of the non-Hodgkin lymphomas were high-grade lymphomas. Patients with AIDS-related malignant neoplasms had higher CD4+ cell counts and viral loads than patients without malignant neoplasms (P < .01, P < .05, respectively). The finding of decreased iron stores in patients with AIDS might aid clinical management of their anemia. The increased incidence of malignant neoplasms, especially lymphomas, in recent years might be related to prolonged survival but with incomplete reconstitution of immune function after antiretroviral therapy.