The preliminary results of the LAL-86 protocol applied to 43 patients diagnosed of acute lymphoblastic leukaemia (ALL) or lymphoblastic lymphoma (LL) between May 1986 and April 1989 are reported. Induction treatment consisted of one or two courses of vincristine, daunorubicin, prednisone, cytosine arabinoside and 6-thioguanine combination therapy. This phase was followed by consolidation treatment, in which VM-26, cyclophosphamide, BCNU and L-asparaginase were added to the former agents. Central nervous system prophylaxis was done with intrathecal methotrexate. Patients under 45 years of age with HLA identical sibs were subjected to allogeneic bone marrow transplantation (BMT) in the first complete remission (CR); when no HLA-identical sibs were available patients were randomised into autologous BMT or maintenance therapy. The remaining patients received maintenance chemotherapy. CR was achieved in 34 ALL patients (79%), 5 were refractory to treatment and 4 died during remission induction. Allogeneic BMT was carried out in 6 cases, autologous BMT in 3, and the remainders received chemotherapy. When performing this review, 7 patients had relapsed and the actuarial probability of 2-year duration of CR was 70%. Sixteen patients have died with a two-year disease-free survival probability of 60%. The preliminary results of the LAL-86 protocol are encouraging, but greater number of patients is needed, as well as a longer follow-up, to assess the effect of chemotherapy and compare these findings to the results of autologous or allogeneic BMT in the first RC.