Therapy for acute lymphocytic leukemia (ALL) has been less successful in adults than in children. Many centers treat all adult leukemia with the same regimen. We have used vincristine and prednisone for initial therapy in 14 adults with ALL since 1971 and have followed a treatment regimen developed for childhood ALL for subsequent therapy as well. Complete remissions were attained in 13, and complications and duration of hospitalization were minimized with this nonmyelotoxic regimen. Central nervous system "prophylactic" therapy was also well tolerated in these adult patients. However, remission duration and survival in our series were similar to those reported by others. That complete remission can be attained in a high percentage of adult patients with ALL through use of relatively nontoxic treatment demonstrates the importance of selecting out this group of patients from all adults with acute leukemia.