Objective：To study the biological characteristics and the differentiation ability of multipotent adult progenitor cells （MAPCs） in vitro and to observe the clinical outcome of MAPC differentiated cells in treatment of ischemic heart disease （IHD） in rabbits, so as to assess the feasibility of transplanting MAPCs in treatment of cardiac infarction. Methods： The bone marrow mononuclear cells were separated from volunteer bone marrow by gradient density centrifugation. The mononuclear cells were separated in CD45 and GlyA fractions by magnetic cell sorting （MACS）. The viability of MAPCs was assessed by trypan-blue assay and their purity were detected by flow cytometry. After cultured with 5-azacytidine （10 μmol/L） for 24 h, MAPCs were subjected to transmission electron microscopic observation. The myogenic cells differentiated from MAPCs were transplanted into the myocardial infarction sites in rabbits and the improvement of their cardiac function was evaluated. Results： The viability of unpurified MAPCs were （96.7±1.7）%, which was not significantly different from that of the purified MAPCs （96.0±2.4） %. The purity of MACS-sorted CD45^- and GlyA^- cells was 〉98%. Thick myofibers were observed by transmission electron microscopy after induction with 5-aza. Four weeks after transplantation, the left ventricle ejection fraction, the movement extent of left ventricle, left ventricle systolic wall thickening and dp/dt of rabbits were all higher than those of the control group and cardiac infarction model group （P〈0.05 or 0.01）, but lower than those of the sham operation group （P〈0.05）. Conclusion： The human MAPCs can differentiate into myogenic cells in the presence of 5-aza. The cardiac function of cardiac infarcted rabbits can be improved by MAPCs transplantation