A total of 25 evaluable adult patients with acute lymphoblastic leukaemia (ALL) were treated with an intensive chemotherapy regime modified from the L17/L17M protocol of the Sloan-Kettering Hospital. There were 18 men and 7 women; their median age was 36 years (range, 13-78). Seven cases had L1 morphology and 18, L2. The immunophenotype was common-ALL in 10, null-ALL in 9, T-ALL in 4 and B-ALL in 1. Of the 25 patients, 14 (56%) achieved a complete remission (CR). The causes of induction failure were partial remission (PR) only in 7 (28%) and hypoplastic death in 4 (16%). Of the 14 CR patients, 11 (78.6%) relapsed. Five patients developed CNS disease. The median disease-free survival and overall survival were only 9 and 13 months, respectively. As the follow-up periods of the surviving patients were short, late relapses may still occur and the overall treatment result is likely to be worse on longer follow-up. The possible causes of this disappointing result are discussed.