Mediastinitis after cardiac surgery is a serious complication with high morbidity and mortality rates. Between December 1989 and April 1992, of 264 patients who underwent cardiac or aortic surgery with median sternotomy, seven (2.6%) developed deep sternal infections with mediastinitis. Six of these patients were treated with debridement, irrigation and delayed wound closure with mediastinal transposition of the greater omentum. Most of the infections were associated with several predisposing factors: cardiac cachexia in the preoperative state, prolonged perfusion time, and respiratory insufficiency in the postoperative period. One of the six patients died of adult respiratory distress syndrome in the postoperative course, but the remaining five patients were discharged with their wounds well healed. Acute and deep mediastinal infection occurred in one patient on the fifth day after cardiac surgery. The infection was successfully treated with radical debridement, two days of intermittent mediastinal irrigation and staged wound closure with omental transposition into the mediastinum. The omental transfer was achieved as follows: after the greater omentum was divided into two pedicles one pedicle was used to fill in the pericardial space and the other was placed between the sternum and the undermined skin. We conclude that early debridement and omental flap transposition are effective in the management of mediastinitis after cardiac surgery.