In 1968-1969, previously untreated patients with ALL were given high dose combination chemotherapy (POMP). This included on days 1-5, i.v., prednisolone 1000 mg/m2; methotrexate (MTX) 7.5 mg/m2; 6-mercaptopurine (6MP) 125 mg/m2; and, on day 1, vincristine 2 mg/m2. Once remission was achieved POMP was given every 2 weeks. The doses of 6-MP and MTX were increased to maximally tolerated levels in all pts. After 6 months, bischloroethylnitrosourea (BCNU) was given for 3 days at 50 mg/ m2 and pts. were randomized to receive POMP monthly for 6 months or no further therapy. Complete remission was achieved in 61/66 pts. (91%). Median remission duration for all 61 pts. was 13 months; 48 pts. completed the initial 6 months of therapy without relapse; 24 were randomized to receive further POMP therapy and 24 to no further therapy. The further therapy group had a median remission of 20 months with 7 pts. still in initial remission. The no further therapy group had a median remission of 11 months with 2 still in initial remission. These differences are significant at the p <.05 level by the generalized Wilcoxon test. A comparable group of 35 pts. had an intermediate remission duration of 17 months. These data indicate that even with intensive therapy in the first 6 months, cure of leukemia will not be possible in the majority of pts. Prolonged therapy is required for improved remission duration.