On the basis of clinical neuropathological evaluation of 48 patients with acute myeloblastic leukaemias the authors analyse the risk factors of leukemic infiltrations developing in the brain. The investigations revealed that the distinct dissemination of leukemic cells in blood is the most important risk factor of such infiltrations. The risk increases significantly in older patients. Survival time and maintenance of high leukocytosis do not intensify the risk of leukemic infiltrations in the brain.