From January 1984 to April 1988, we treated 20 patients with adult lymphoblastic leukemia (ALL) and 2 patients with lymphoblastic lymphoma with a protocol which we modified L-10M of Sloan-Kettering Cancer Center. Since the median follow up time is now over 5 years, we report the most recent outcome. Thirteen patients were male and 9 were female. The median age was 31, ranging from 15 to 71 years of age, and there were no Ph1 positive patients. The complete remission (CR) rate was 81.8%. Median CR duration was 32 months and the 5-year continuous CR rate was 33.3%. No significant prognostic factor for CR rate was found. Age at achievement CR and duration were significant prognostic factors. The 5-year continuous CR rate of patients below 35 years old was 54.5%. In this group the leukocyte count was a significant prognostic factor. All patients with a leukocyte count above 1 x 10(4)/microliters relapsed. However, in patients with a WBC below 1 x 10(4)/microliters, the 5-year continuous CR rate was 75%. Based on these results, it seems reasonable to treat patients with ALL by different therapeutic strategies according to the risk factors.