Green tea polyphenols have recently attracted medical attention as bioactive agents with anticancer, antimicrobial, and antiviral effects. We discovered their new usage as preservative agents for tissue transplants. We preserved rat aortas in a DMEM solution containing polyphenols extracted from green tea leaves. The preserved aortas retained original structures and mechanical strength, and were devoid of any undesirable cell secretions for over a month under physiological conditions. In addition, aortas from Lewis rats preserved for a month and transplanted to allogenic ACI rats completely avoided rejection by the host, suggesting that the polyphenols have immunosuppressive actions on the aortic tissues. From these results, we conclude that polyphenol treatment of aortic tissue transplant can maintain its viability for extended periods of time either before or after transplantation, and the method can be applicable to other transplantation situations.