We report the first known case of fulminant bone marrow necrosis (BMN) occurring after infusion of fludarabine monophosphate in a patient with recurrent low-grade non-Hodgkin's lymphoma (NHL). Extensive BMN is characterized by the development of fever, bony pain, a leukoerythroblastic peripheral blood film, variable degrees of pancytopenia and elevations in lactate dehydrogenase and alkaline phosphatase. The diagnosis of BMN is rarely entertained ante-mortem. Although the precise role chemotherapy may have played in triggering fatal BMN remains speculative, we alert clinicians to be aware of this entity as more patients with indolent lymphomas and leukemias are treated with this and other potent nucleoside analogs.