Bone marrow necrosis (BMN) in acute leukemia is a rare histopathological entity at the time of initial diagnosis. However, it represents an important diagnostic and prognostic challenge. Two cases of BMN are reported: a 44-year-old patient with B cell precursor (BCP) acute lymphoblastic leukemia (ALL) and a 27-year-old man with FAB-M5 acute myeloid leukemia (AML) who both presented with bone marrow failure and extensive necrosis. From these clinical cases, we conducted a brief review of the literature.