This paper reports a study of the Cancer and Leukemia Group B (CALGB) comparing daunorubicin (DNR) or mitoxantrone (DHAD) in induction followed by multidrug intensification over 8 months in adult patients with acute lymphocytic leukemia (ALL). A total of 164 newly diagnosed patients were randomly assigned to either DNR or DHAD plus vincristine, prednisone and methotrexate given intravenously (i.v.) and interthecally (i.t.). Patients received four more intensification courses of chemotherapy and then all therapy was stopped. Central nervous system (CNS) prophylaxis consisted of nine infusions of intermediate dose methotrexate (MTX) and intrathecal MTX. DHAD and DNR were equally effective in producing complete remissions (63 and 65%, respectively). The estimated median remission duration is 10.2 and 12.3 months for the DHAD and DNR arms, respectively (p = 0.56). This study was stopped earlier than planned when it became apparent that remission duration for both arms was shorter than seen in our prior study in which all patients received more than 1 year of maintenance therapy. The estimated median survival is 18.3 and 20.6 months for the DHAD and DNR arms, respectively (p = 0.90). Younger patients and patients with a pre-treatment white blood count of less than 30,000/microliters had a significantly longer remission duration and survival. Eleven per cent of patients who achieved a complete remission have had a CNS relapse to date, which is not different from the rate in our prior study using cranial irradiation and i.t. MTX, implying that intermediate dose MTX with i.t. MTX may be as effective as cranial irradiation and i.t. MTX. This study suggests that some form of maintenance chemotherapy is required for the eradication of residual leukemia cells.