Aim. To study the expression of chimeric genes in bone marrow cells as prognostic factors of the course of acute lymphoblastic leukemia (ALL) in children and evaluate their role in resistance to cytostatic chemotherapy. Methods. The AF4-MLL, BCR-ABL, E2A-RVX, TEL-AML1 chimeric gene expression level was determined by RT-qPCR. Results. The AF4-MLL oncogene was not expressed in children during remission, and the expression of all other studied oncogenes was at a low level. In conditions of relapse, there was no expression of the TEL-AML oncogene and a high expression of the BCR-ABL. Conclusions. The development, course, and survival of all patients largely depend on the expression of AF4-MLL, BCR-ABL, E2A-PBX1, TEL-AML chimeric genes in the bone marrow; this should be taken into account when detecting early relapses in patients after chemotherapy.