Bone marrow necrosis (BMN) is a rare intravitally recognized finding in acute leukaemia with an uncertain clinical significance. The clinical events in 4 patients with AML, ALL, AMoL and blastic transformation of CGL in whom bone marrow cytology and histology revealed BMN are reviewed. One patient with BMN at clinical presentation of AML entered complete, long lasting remission with marrow restoration after the standard DAT therapy. In the three remaining patients survival after BMN diagnosis was 6, 11, and 14 weeks. Clinical, haematological, histological and marrow scanning findings and their significance for early diagnosis and means to asses the extent and evaluation of BMN will be discussed. In contrast to the most earlier reports, BMN does not appear to confer a poor prognosis in all patients with blastic leukaemia.