A consecutive series of 1083 patients undergoing open-heart surgery was prospectively observed for infectious complications. Postoperative mediastinitis developed in 15 cases (1.4%). Surgical management of the mediastinal complication consisted of careful debridement of the sternal wound and the anterior mediastinum, followed by continuous retrosternal irrigation with an antiseptic or antibiotic solution after sternal refixation. The mean duration of mediastinal irrigation was 12.7 days. This treatment was successful in 13 of the 15 patients. In 2 of the 13, however, secondary refixation became necessary to stabilize the fragmented sternum. Repeated refixation with mediastinal irrigation was effective in one of these patients. The other underwent removal of the fragmented sternum followed by muscle plasty, but died unexpectedly of aortic dissection when signs of infection were subsiding. Two patients (13%) treated with closed chest irrigation died of recalcitrant mediastinal infection.