The application of recent discoveries in the field of molecular oncology to acute myeloid and lymphoblastic leukemia has provided new insights into the pathogenesis and natural history of these diseases. Cytogenetic abnormalities and the detection of mutations or abnormal expression of certain oncogenes or tumor suppressor genes now provide powerful prognostic information to guide choice of therapy and prediction of response. Randomized trials of intensive postremission chemotherapy have now confirmed improved leukemia-free survival with the use of high-dose cytarabine or allogeneic or autologous bone marrow transplantation. Progress in the treatment of acute myeloid leukemia and acute lymphocytic leukemia in the elderly, where the prevalence of these diseases is likely to increase as our population ages, has been more modest. There is still a need for the evaluation of new treatment strategies in previously untreated patients with acute leukemia, despite the progress that has been reported during the past year.