Objective Isohemia-reperfusion injury oecurred during heart transplantation may result in failure of grafts and the death of receivers perioperatively. Over expression of TGF-β1 in the myocardium therapeutically was shown to be help-ful in limiting the reperfusion injury to the grafts. The study was designed to investigate the role of Ad. mTGF-β1 gene transfec-tion during ischemia-reperfusion injury in vitro after heart transplantation in rats and the possible mechanisms. Methods The model of heterotopic cardiac transplantation was established by Heron's technique with cuff vessel anastomosis. Animals were divided into 3 groups: in group A ( n =6, control group), the donor hearts were perfusod with 6 ml of Stanford University cardio-plegic solution via coronary arteries at 4℃ for about 40 minutes; in group B ( n =6, vector alone group), the donor hearts were perfused with 6 ml of Stanford University cardioplegic solution containing 5 × 10~9 plaque-forming units( pfu)/gram of the vec-tor, and in group C (study group), the donor hearts were perfused with the solution containing 5 × 10~9 pfu/gram vector with mTGF-β1. The donor hearts were observed with an electro-microscope. The expression of mTGF-β1 in the grafts was identified with immunohistochemical staining. Gene products expressed in tissues were quantified by one step RT-PCR. Activities of SOD ,MDA ,MPO in the grafts were measured. Results At 8 hours after transplantation, mTGF-β1 and its expression were de-tected by means of RT-PCR and immunohistochemical staining in the rats of group C. Expression scores of foreign gene were significantly higher in groups A and B. The apoptotic index of the myocardial cells in group C was lower than those in groups A and B. The activity of SOD was higher in group C than those in groups A and B, though the activities of MDA and MPO were decreased. Conclusion The study demonstrated that gent transfer in vitro via coronary artery was effective. Ad. mTGF-β1 gene transfection in vitro ameliorates the myocardial ischemia-reperfusion injury in rats, for which heart transplantation was per formed, increases the activity of SOD, and decreases the activities of MDA, MPO.