Abstract: Objective To explore the feasibility of labeling ovine bone marrow stromal cells (BMSCs) with CM-DiI for intracardiac tracking. Methods Ovine BMSCs were labelled by CM-DiI, and then cultured and monitored by fluorescence microscopy. Tracking of BMSCs was done after intramyocardial injection of CM-DiI-labeled BMSCs into infarction and peri-infarction area and examined by histology and fluorescence microscopy. Results BMSCs can be labeled by CM-DiI. The labelled BMSCs (D-BMSCs) showed red auto-fluorescence. In vitro study the D-BMSCs didn't show to alter the morphology of mesenchymal stem cells, and maintain strong fluorescence after subpassage culture. Flow cytometry analysis demonstrates that there is no difference in cell proliferation between D-BMSCs and BMSCs. CM-DiI labeling did not in fluenced multipotent capacity of BMSCs proved by inducing differentiation into adipose, chondrocyte and osteoblast. One week after intramyocardial transplantation, the D-BMSCs maintain strong fluorescence, clearly showing the location and the morphological characteristics of the implanted BMSCs. Conclusion CM-DiI labeling can be used as a stable fluorescent intracardiac tracking system.