Retrosternal pericardial adhesion formation constitutes a major hazard during re-do coronary artery surgery. To determine whether an onlay parietal pleural flap over the internal thoracic artery bed would reduce pericardial adhesions after coronary artery grafting, 16 sheep underwent a median sternotomy and both internal thoracic arteries were harvested. On the randomly selected study side, a dissected pleural flap was used to cover the internal thoracic artery bed, the opposite side was left uncovered as a control. Half of the sheep were sacrificed at a median of 102 days (range, 93-109 days), the remainder at a median of 176 days (range, 165-183 days). Two independent observers blinded to the initial operation scored the degree of postoperative adhesions. There was a significant decrease in adhesion formation on the study side covered by the mobilized pleural flap, compared to the control side. There were no increases in pulmonary morbidity or sternotomy wound problems from raising the lateral pleural flap. This simple technique appears to be an effective method of preventing adhesion formation following coronary artery bypass grafting utilizing the internal thoracic artery.