Hematological diseases may cause acute hepatic failure and are seldom sought. We report two cases illustrating this situation. A 16-year-old male presented with an acute liver failure: a bone marrow biopsy showed complete infiltration with lymphoid type blasts. A flow cytometry confirmed the presence of an acute lymphoblastic leukemia. The patient died days later. A 20-year-old female presented with acute liver failure: due to a pancytopenia, a bone marrow biopsy was performed, which confirmed the presence of an acute lymphoblastic leukemia. Chemotherapy was started immediately. The patient had a favorable evolution.