Objective To analyze the changes of gene expression profiles during the process that human bonemarrow mesenchymal stem cells (hBMSCs) are induced to differentiate into cardiomyogenic cells with 5-azacytidine (5-aza). Methods hBMSCs were isolated from marrow of obsolete ribs and induced with 5-aza. Then immunocytochemicalstaining was used to detect the expressions of α-actin, cardiac troponin T (cTnT), and connexin 43, and the percentage ofcTnT positive cells was tested with flow cytometry. In the process of differentiation, variation of gene expression was screenedwith Genechi ps Operating System of human gene expression profiles. And the differentially expressed genes were functionallyanalyzed and hierarchical clustered. Results When BMSCs were induced in vitro with 5-aza, part of the cells turnedinto myogenic cells morphologically. Before induction, immunocytochemical staining for α-actin and cTnT showed sl ightpositive and for connexin 43 showed negative. While after 3 weeks of induction, immunocytochemical staining for α-actin,cTnT, and connexin 43 showed all positive. With flow cytometry, the percentage of cTnT positive cells was 7.43% ± 0.02%before induction, but it was 49.64% ± 0.05% after induction. During differentiation, 1 814 differentially expressed geneswere reported by gene chi ps. Of them, 647 genes were divided into 5 groups with hierarchical clustering. They had variousbiological functions, involving signal transduction, cell metabol ism, prol iferation, differentiation, development, andtopogenesis. Conclusion hBMSCs can differentiate into cardiomyogenic cells with the induction of 5-aza in vitro. Multi plegenes related with signal transduction, transcri ption, and growth factors are involved during this process.