Between June 1991 and September 1992, 80 patients with adult acute lymphoblastic leukemia (ALL) (newly diagnosed, n = 68; relapsed or refractory ALL, n = 7; lymphoid blast transformation of Philadelphia chromosome-positive chronic myelogenous leukemia [LT-CML], n = 5) were managed with a combination regimen consisting of idarubicin 36, 20, or 10 mg/m2 plus vincristine, L-asparaginase, and prednisolone (IVAP-1, -2, -3). Three patients with LT-CML and four with relapsing ALL had a complete remission. In the group of newly diagnosed patients aged 15 to 60 years treated with IVAP-1, the complete remission rate was only 44% due to the high incidence of toxic deaths. In contrast, 39 of 44 cases who subsequently received IVAP-2 achieved a complete remission (89%, P = .001), as did 62% of elderly patients who received IVAP-3. Hematologic and nonhematologic toxicity was significantly reduced with IVAP-2 compared with IVAP-1. The use of recombinant human granulocyte colony-stimulating factor in 24 patients was not associated with a reduced duration of granulocytopenia less than 0.5 x 10(9)/L, although there was a lower incidence of documented infections in patients receiving granulocyte colony-stimulating factor than in controls. Post-remission intensification with idarubicin-based courses, high-dose therapy with autologous bone marrow stem cell rescue, and rotational weekly therapy was feasible and its toxicity was manageable. These preliminary findings indicate that IVAP-2 (idarubicin 20 mg/m2) is a highly effective and well-tolerated regimen for remission induction of adult ALL.