Development of stem cell - based myocardial therapy has been leading to myocardial regenerating success because of therapeutic contribution of mesenchymal stem cells. One of the important roles of mesenchymal stcm cell is differentiation potential. The cardiomyoeyte differentiation, involving both phenotype changes and genotype changes, is considered a chain of events in temporal and spatial regulations. Therefore, doing research on the eardiomyogenesis mechanism of mesenchymal stem cells is essential. The goals of research are to dit1erentiate human umbilical cord blood - derived mesenchymal stem cells into cardiomyocytes and evaluate the in vitro changes of myocardial - related transcript expression during differentiation. Umbilical cord blood - derived mesenchymal stem cells isolation was followed previously - published procedures and their markers were confirmed by flow cytometry techniques. The transcript expression of several myocardial specific genes was assessed by RT-PCR before and after induction. The results showed that isolated mesenchymal stem cells were capable of strong proli teration and differentiation potential into adipocytes. They were also positive tor CD44, CD90, CD166, dimly positive for CDI4, CDJ06 and simultaneously negative for CD34, CD45, HLA-DR. Mesenchymal stem cells exhibited GATA4, alpha - cardiac actin betore differentiation. Alter treatment with cardiomyogenie medium, mesenchymal stem cells morphologically changed into cardiomyocyte - like cells and expressed more other myocardial genes, like Nkx2.5, MEF2c, troponin T, alpha, heta ~ myosin heavy chain, desmin, HCN2 and h8NP. However, in this study, there was no evidence to prove any pulsation of induced cells. The results showed that mesenchymal stem cells from human umbilical cord blood had differentiation potential into cardiomyocytes although the morphological changes and the transcript expression were not sufficient for their ditferentiation to mature cardiomyocytes.