The transcriptional activity of RHOA, SEMA3B, and CKAP2 genes was assessed in blood samples of leukaemia patients and healthy donors. In the blood of healthy donors, RHOA and CKAP2 gene expression was not detected, and low SEMA3B gene expression was observed. Significant elevation of expression of all the three genes was shown in the case of acute myelogenous leukaemia. In cases of remission of acute lymphoblastic leukaemia and myelodysplastic syndrome, no expression of all three genes was detected. The long isoform of the CKAP2 gene was highly expressed in most analysed types of leukaemia.