Bone marrow necrosis (BMN) is mostly diagnosed at postmortem examination. It has been observed in association with acute leukemia and other malignant diseases. We report here BMN in two patients with acute myeloid leukemia (AML) and one with acute lymphocytic leukemia (ALL) in whom the diagnosis was made while alive. Two patients died because of intracranial bleeding. One with AML (M5) developed BMN one week after he was treated with a second course of chemotherapy: he had a complete recovery and remains in remission almost five years after the diagnosis. We conclude that antemortem diagnosis of BMN is technically difficult, but as it is not always associated to a fatal prognosis, an early diagnosis and vigorous supportive therapy should be attempted.