Low dose Ara-C (10-15 mg/m2) was administered subcutaneously in 1-5 courses of 14 to 21 days to 16 patients with acute nonlymphoblastic leukaemia, mostly in elderly persons and/or with pancytopenia in whom conventional chemotherapy was contraindicated or ineffective. 18 of the 26 patients were females and 8 males. The mean age was 54.9 years ranging from 31 to 81 years. Mean duration of treatment was 15.2 days. Five complete remissions and three partial remissions were obtained. The mean duration of complete remission was 4.7 months and the mean duration of partial remission was 6.7 months. Aggravation of cytopenia during the treatment and hypocellularity of bone marrow aspirates at the end of therapy suggest that low dose Ara-C exerts its main activity by suppression of leukaemic proliferation rather than by induction of differentiation in malignant cells. Our results show that low dose of Ara-C could be valuable alternative treatment in patients with contraindications or ineffectiveness of conventional intensive chemotherapy.