Intensive chemotherapy according to the West Berlin protocol was given in 15 children with acute lymphoblastic leukaemia with bone marrow recurrence after an initial remission period of 12 months or longer. Treatment of first episode had followed the 1971 recommendation of the German working group for research and treatment of childhood leukaemia (Memphis VII protocol). One child died from Pseudomonas septicaemia during relapse treatment, the other 14 achieved renewed complete remission for 4 to 50 months. All 5 children in whom the initial remission had lasted less than 20 months had another recurrence after 12 to 17 months. Four out of the 9 patients with an initial remission period of 20 months or longer had another bone marrow relapse after 5 to 36 months. Five children are in continuing second remission for 26 to 50 months, 4 of them already off treatment (for the last 5 to 12 months). The results show that in certain cases of relapse of acute lymphoblastic leukaemia of childhood a new chance of long-term remission and perhaps cure exists, particularly after long initial remission, when a suitable intensive treatment regime is followed.