The development of severe pericardial adhesion after cardiovascular surgical procedures often increases the risk of injuring the heart, great vessels, or extracardiac grafts during resternotomy. Several pericardial substitutes have been tested in an attempt to facilitate reoperation with inconclusive results. This study was designed to evaluate the applicability of two different materials as pericardial substitutes to minimize the pericardial adhesion and epicardial reaction. A procedure for induction of pericardial adhesion was carried out in 30 rabbits. Rabbits were divided into three groups of ten rabbits each: Group 1[control, simple pericardial closure]: Group 2[bovine pericardium as pericardial substitute]: Group 3[e-polytetrafluoroethylene surgical membrane, e-PTFE as a pericardial substitute]. Bovine pericardium or e-PTFE surgical membrane was interposed between the sternum and the heart. Rabbits were sacrificed at 4 weeks after operation. The development of adhesions and epicardial reactions were graded as: none [I]; minimal[II]; moderate[Ill]; and severe[1V]. Histologic studies of the substitute, the pericardium, and the epicardium were performed. The results were as follows; l. In group 1[control group], the degree of pericardial adhesions were grade I in none, grade II in 1, grade III in 3, and grade 1V in 6 animals. Epicardial reactions were grade I in none, grade II in 3, grade K in 4, grade 1V in 3 animals respectively. 2. In group 2[bovine pericardium], the degree of pericardial adhesions were grade I in 1, grade II in 5, grade III in 3, and grade 1V in 1 animal. Epicardial reactions were grade I in 1, grade II in 2, grade III in 4, and grade 1V in 3 animals respectively. 3. In group 3[e-PTFE], the degree of pericardial adhesions were grade I in 7 animals, grade II in 2, grade III in 1, and grade g in none. Epicardial reactions were grade I in 4, grade II in 3, grade III in 2, and grade IV in 1 animal respectively. Pericardial adhesions more than grade II were 90.9% in group 1, 40 % in group 2, and 10% in group 3. Pericardial adhesions were significantly reduced in group 3 compared to group 1 or 2. Epicardial reactions more than grade II were 70 % in group 1, 70 % in group 2 and 30 % in group 3. We concluded that this 0.1mm thick polytetrafluoroethylene surgical membrane is a suitable pericardial substitute to minimize the development of pericardial adhesion or epicardial reaction following cardiovascular surgery.