Prognostic factors were related to remission duration among 179 standard risk newly diagnosed acute myeloid leukemia (AML) patients who received identical induction and consolidation therapies. Following a bromodeoxyuridine infusion, labeling indices of bone marrow aspirate/biopsy, durations of S-phase and cell cycle (Tc) were determined. Patients with slowly cycling myeloblasts had longer remissions (Log rank p=0.03) than those with rapidly cycling myeloblasts. Multivariate analysis demonstrated that both WBC and Tc contributed to remission duration (p=0.01 and 0.005 respectively). Patients with slowly proliferating leukemias have longer remissions probably due to slower regrowth of leukemia between chemotherapy courses.