Increasing numbers of bone marrow aspirates and core biopsies are done in very elderly people; there is little published literature regarding the usefulness of bone marrow biopsies in these patients. We undertook a retrospective review of 119 bone marrow aspirates and biopsies from patients 85 years or older. These procedures were performed for a variety of abnormalities, including unexplained cytopenias; evaluation of a known myelodysplastic syndrome; suspicion or follow-up of plasma cell myeloma, thrombocytosis, or leukocytosis; and suspicion or staging of lymphoma. When staging or follow-up biopsies were excluded, 34 (43%) of 79 yielded specific diagnoses. Follow-up was available for 45 patients, and of these 45, 20 patients received therapy: 17 were treated with an abbreviated or modified regimen, and 12 were treated for leukemia/lymphoma. Therapy failed in all patients. As a result of these biopsies, relatively few patients received more than supportive treatment, suggesting that higher thresholds for biopsy for cytopenias may be indicated.