Bone marrow necrosis (BMN) is a relatively uncommon clinicopathologic entity. The etiology is diverse, and malignancy, especially hematopoietic in origin, is the most common underlying disease of BMN. In this retrospective analysis, cases with BMN were re-evaluated for etiology, histopathologic details, and clinical manifestations. In the last 8 years, 23 cases of BMN were detected among the 1,083 bone marrow (BM) biopsies, and the prevalence was found to be 2.2%. Three of these 23 cases with BMN were children, and 20 cases were in adults. Sixteen of these cases (80%) had underlying malignant disease, and four (20%) had nonmalignant disease. Among the malignant cases, three cases had acute myeloblastic leukemia (AML), four had relapsed Hodgkin's disease (R-HD), one had acute lymphoblastic leukemia (ALL), two had chronic myelocytic leukemia (CIVIL), two had non-Hodgkin's lymphoma (NHL), three had disseminated intravascular coagulation (DIC) associated with metastatic solid tumor, and one had myelodysplastic syndrome/myeloproliferative syndrome (MDS/MPS). Among the nonmalignant cases, two had tuberculosis infection, one had anti-phospholipid syndrome (APS), and one had a history of drug ingestion. The most common symptoms were bone pain, fever, fatigue, and jaundice. The most common laboratory findings were variable and associated with underlying disease, but anemia, leukopenia, thrombocytopenia, and high LDH and alkaline phosphatase levels were detected in the majority of the cases, as was also seen in other series. BMN was graded according to the extent of necrosis in the BM biopsy, and necrosis was extensive in 12 cases, moderate in five cases, and mild in three cases. Increased reticulin was found in 16 cases; four cases had severe, eight had moderate, and four had mild fibrosis, and this was found to be an interesting accompanying finding in BMN. In conclusion malignancy is the most common cause of BMN but some nonmalignant conditions such as tuberculosis and APS may be the underlying cause of BMN. (C) 2002 Wiley-Liss, Inc.