Bone marrow aspirates and biopsies from 35 AIDS/AIDS-related complex patients, consisting primarily of intravenous drug abusers, were studied. The most common findings included hypercellularity (86%), plasmacytosis (63%), reticular fibrosis (50%), and lymphocytosis (37%) occasionally admixed with histiocytes. Granulocytic hyperplasia was present in 27 patients (77%). Erythrocytic hypoplasia was observed in 15 patients (43%). Megaloblastic changes of intermediate form were seen in two cases and serous fat atrophy was noted in another three patients. One M. tuberculosis granuloma, a foreign body granuloma and two granulomas of undetermined etiology were seen, each in separate patients. A previously unreported focal vascular proliferation was seen in one case. The majority of cases showed increased stainable iron. Some of our findings are at variance with previous reports. This may reflect differences in patient population, geographic distribution, risk factors and epidemiologic mode in our cases.