The authors tried to test the value of some clinical and laboratory characteristics for the prognosis of acute lymphoblastic leukaemia (ALL) in a group of 69 children treated according to three different protocols. The results were evaluated by methods of one-dimensional and multidimensional analysis. The absolute number of blasts in the peripheral blood stream and initial leucocytosis during establishment of the diagnosis proved to be the most important risk factors influencing the prognosis of the patients. Other adverse signs for the prognosis of ALL in the group were a mediastinal tumour, L2 type of leukaemic blasts according to the morphological FAB classification and age above 10 years when the diagnosis was established. The patient's sex, immunophenotype of the leukaemic blasts, chromosomal abnormality of the karyotype in the leukaemic cells, marked hepatosplenomegaly, thrombocytopenia, haemoglobin values and PAS reaction in the blasts, did not affect the therapeutic results in the author's group of patients.