Endothelial colony forming cells (ECFC) have clear self-renewal capacity in culture and can undergo neovascularisation and promote blood reperfusion in vivo. Co-administration of mesenchymal stem cells (MSC) with ECFC have greater potential to be used as a cell therapy in treating ischemic cardiovascular disease. However, immunosuppression is necessary to improve cells engraftment during allogeneic cells transplantation. Nevertheless, it remains unresolved the impact of the immunosuppressant cyclosporine on injected ECFC. Here we used a hind-limb ischemia model in mice given either ECFC+MSC (weekly injection) with or without cyclosporine (daily injection). Cells were injected directly into the muscle adjacent to the severed right femoral artery. Each mouse was imaged weekly using a High Resolution Laser Doppler to ascertain level of blood reperfusion. Surprisingly, mice receiving only ECFC+MSC had a significant increase in reperfusion (74.77%±2.9;**p<0.01) compared to mice receiving both ECFC+MSC and cyclosporine (46.1%±3.4) at Day22. Further validation using in vitro Matrigel tube and colony forming assays showed a significant reduction (***p<0.001) in tube formation and ECFC colony forming capacity (**p<0.01) following cyclosporine treatment. This is the first study to demonstrate the negative effects of cyclosporine on ECFC and has the potential to change the design of future cell therapy for patients.