The haematological toxicity of the induction phase of chemotherapy for acute lymphoblastic leukaemia (ALL) was compared in two cohorts of patients. The principal difference between these two cohorts was the mode of administration of the anthracycline, daunorubicin (DNR). Both groups received four-drug induction chemotherapy, which produced a high remission rate. Those receiving DNR on days 1 and 2 experienced a profound but shorter period of neutropenia and more severe thrombocytopenia than those who received the DNR weekly. The pattern of hospitalisation and support facilities in the individual unit may determine which regimen is to be preferred. These observations are relevant for the newly diagnosed patient in whom an anthracycline is retained in the induction therapy for ALL.