The paper presents the experience of the Polish Paediatric Leukaemia/Lymphoma Study Group in the treatment of high-risk acute lymphoblastic leukaemia in children using a new version of the New York (1997-1999). Protocol with treatment intensity adjusted according to the age of the patients. From April 1997 to December 1999 a group of 49 children with leukocytosis ranging from 50 900/mm3 to 580 000/mm3 (median 122 000/mm3) and 6 children with leukocytosis below 50 000/mm3 and poor response to steroids were treated with this protocol. Children below 10 years (43 patients) were treated according to the previous protocol, children above 10 years (12 patients) were treated with intensified protocol (high doses of ARA-C in consolidation and intermediate doses of Mtx in maintenance). Induction was identical for all patients. Complete remission was achieved in 92.6% patients. There were 2 relapses. Six children died - 3 without remission, 2 due to a relapse, 1 due to treatment complications. The current opinions concerning classification of HRG-ALL and treatment possibilities in this group of children are discussed.