In order to reduce the toxicity of the otherwise very effective childhood ALL treatment protocol BFM 76/79 asparaginase was omitted from the 4-drug induction regimen and placed as single drug before the intensification phase. In addition the effect of 3-monthly intermediate dose methotrexate (ID-MTX) pulses versus conventional vincristine (VCR) pulses during maintenance therapy was studied. Of 145 evaluable patients 124 (85.5%) survive in continuous and complete remission (CCR) at a median observation time of 21 (1,5-47) months. The expected rate of patients in CCR at 4 years is 75% respectively 80% after exclusion of 4 patients with fatal complications and one remission failure. These relapse free survival data re equal to the BFM 76/79 and 79/81 results. There was very few therapy related morbidity and no mortality from the COALL-80 induction therapy modification. The intensification phase, however, which was adopted from the BFM study without modification was difficult to manage and was not free of life threatening mostly infectious complications which were fatal in 4 cases. ID-MTX pulses did not prove superior to conventional VCR pulses. The relapse rate in patients with the c-ALL subtype was markedly lower than in any other subtype, remarkably also than in the undifferentiated type.