A total of 527 children with acute lymphoblastic leukaemia (ALL) from the most frequent risk groups: standard risk group (SRG) and intermediate risk group (IRG) were treated between 1987 and 1991 according to an intensified treatment program (based on the BFM protocol) including the use of an intermediate dose of methotrexate in the IRG. A comparison of the treatment results in this group from 513 children treated between 1981 and 1987 indicates that the chance for a 6 year event-free survival has increased to 73% (previously 55%).