Purpose: To demonstrate the feasibility of a longitudinal monitoring of transplanted cell survival in living animals, accomplished with optical imaging techniques and pharmacological interventions. Materials and Methods: Murine embryonic cardiomyoblast (H9c2) cells were transfected with Ad-CMV-Fluc with different MOI (1, 10, 100) and different cell numbers (10⁴~3x10⁶, MOI=100) to be injected into thigh muscle of nude mice (n=15). After getting the cord blood stem cells (CBSCs), cells were also transfected (MOI=100) overnight with Ad-CMV-Fluc. Sprague-Dawley rats (n=12) were given intramyocardial injections containing 1x10⁶ CBSCs expressing Fluc. Optical bioluminescence imaging was then conducted using a charged-coupled device camera (Xenogen), beginning on the day after the transplantation. Groups of mice were then intraperitoneally injected with cyclosporin (5 mg/kg) or tacrolimus (1 mg/kg), in an attempt to determine the prolongation of cell survival, and these values were then compared to the cell survival values of the non-injected group. Results: Bioluminescence signal intensity was 3 to 30 times higher according to the MOI (100, 10, 1) all through the study periods (from day 1 to day 5). There was a strong correlation between intensity of imaging signal and the injected cell numbers (r=0.88). Bioluminescence signals were determined to be present for 6 days after cardiac transplantation. The four mice who received either cyclosporin or tacrolimus displayed cardiac bioluminescence signals for a period of 8 days after transplantation. We observed significant differences between the treated group and the non-treated group, beginning on day 3 (tacrolimus; 26500짹4340, cyclosporin; 27200짹3340, non-treated; 9630짹1180, p<0.01), and persisting until day 7 (tacrolimus; 12500짹2946, cyclosporin; 7310짹1258, non-treated; 2460짹160, p<0.01). Conclusion: The locations, magnitude, and survival duration of the stem cells were noninvasively monitored with a bioluminescence optical imaging system. In rat cardiac CBSC transplant models, transient immunosuppressive treatment with tacrolimus was shown to improve donor cell survival.