Increased dosages of cytosine arabinoside (Ara-C) have been shown to be active in remission induction and consolidation treatment of patients with primary refractory acute lymphoblastic leukemia (ALL) and lymphoblastic non-Hodgkin's lymphoma (lyNHL). From August 1983 to December 1986 we treated 25 patients with ALL (9) and lyNHL, stage III and IV (16), median age 22 (range 15–48 yr) with a protocol consisting of remission induction with vincristine, prednisone, adriamycine and Ara-C (1 g/m2 twice daily as 2-h infusion d1–6) and intrathecal methotrexate, followed by consolidation courses with vincristine, prednisone, adriamycine and Ara-C (3 g/m2, twice daily as 2-h infusion d1–4) and intrathecal methotrexate. Some patients received CNS and/or mediastinal irradiation. No maintenance was given. 18 patients (72%) achieved complete remission (5 of the 11 previously treated and 13 of the 14 previously untreated patients). Consolidation courses were given to 17 patients. 5 of them relapsed in the bone marrow (3), skin (1) and CNS plus bone marrow (1) at 5, 5, 6, 6 and 24 months. The duration of complete remission ranged from 5 to 51+ months; the median could not yet be calculated. Short-term intensive treatment might be a worthwhile approach for ALL and lyNHL.