In the course of a 12-year period the authors treated at the Paediatric Department of the Regional Institute of National Health in Banská Bystrica 72 children with acute lymphoblastic leukaemia according to four protocols. Complete remission was achieved by 67 children, i.e. 93%. None of the children died from complications of treatment during complete remission. A relapse during treatment or soon after its termination occurred in 23 children, i.e. 31.9%. A second complete remission was achieved in 15 children, i.e. 65.2%. During the second complete remission seven children survive for 0.5-91.5 months. Twenty children died, i.e. 27.8%. All children had at the time of death signs of malignant disease. Fifty-two children survive at present for 1-132 months. The cumulative ratio of surviving children in the 12th year since the diagnosis is 0.57, the cumulative ratio of children in initial complete remission in the 12th year is 0.51.