Abstract: AIM To investigate the effect of adipose tissue-derived mesenchymal stem cells (ADMSCs) transplantation on myocardial injury and cardiac function in rats with dilated cardiomyopathy (DCM). METHODS Eighty Wistar rats were given doxorubicin by intraperitoneal injection to induce DCM and were randomly divided into two groups: namely, treatment group and control group. The ADMSCs isolated and cultured in vitro were transplanted into DCM rats through epidium. The rats in the control group were treated with IMEM medium of the same volume. All the rats were cultured for 4 week and then were killed to obtain heart samples, and the survival and differentiation of transplanted cells were observed. Before transplantation and 4 weeks after transplantation, all the rats were examined by ultrasonic cardiogram test and haemodynamics test to determine the cardiac function. RESULTS ①By gross observation, histological observation and cardiac function determination showed that DCM model was successfully established in rats. ②The ADMSCs labeled with DAPI were found in the samples derived from recipient site 4 weeks after transplantation. Meanwhile, some DAPI labeled positive cells were found by immunohistofluorescence staining, which also presented positive result by TnT staining, and the array of these cells was in accordance with that of myocardial cells. ③Comparison of heart function of rats in the two groups 4 weeks after transplantation showed that the left ventricular end-diastolic pressure (LVEDV) and left ventricular end-systolic pressure (LVESV) reduced in the ADMSCs transplantation group as compared with those in the control group (P<0.05,P<0.01). LVSV, EF, LVSP, +dp/dtmax, and -dp/dtmax increased (P<0.05,P<0.01). CONCLUSION Transplanted ADMSCs may survive and differentiate into myocardial cells and improve the heart function in rats with dilated cardiomyopathy.