Nowadays, the analysis of hematopoiesis in patients with acute lymphoblastic leucosis includes only quantitative characteristics of residue myeloid process of bone marrow. The evaluation of myelodysplasia is unexplored still. The analysis of myelopoiesis was carried on sampling of 108 patients with primary acute lymphoblastic leucosis (27 - T-acute lymphohlastic leucosis, 81 - B-acute Iymphoblastic leucosis). The characteristics of dysplasia of granulocytes, erythroid cells and megakaryocytes were based on the parameters of WHO classification of acute myeloid leucosis (2001). The monolinear dysplasia was established in 35 patients (32.4%). multilinear dysplasia--in 9 patients (8.3%). Under T- acute lymphoblastic leucosis the bilinear dysplasia was detected reliably more often and absence of dysplasia more rare than under B-acute lymphoblastic leucosis. The signs of dysplasia of various myeloid lines had no inter-correlation and had no dependencies from indicators of expression of early antigens (CCD34 and TdT) and myeloid antigens (CD13, CD33). The comparison of factual data with indicators of dysplasia under acute mteloid leucosis (181 patients) demonstrated that rates of uni- and multilinear dysplasia under T-acute Iymphoblastic leucosis and acute myeloid leucosis have no significant difference. The myelodysplasia is detected reliably (more often under B-acute lymphoblastic leucosis as compared with acute myeloid leucosis.