From a series of 2594 patients undergoing open-heart surgery, 39 had sternal or costochondral infections. Most of these infections were associated with a number of predisposing factors: prolonged perfusion time, excessive postoperative bleeding, depressed cardiac output in the postoperative period and a history of re-exploration for the control of hemorrhage. One important factor was the use of bilateral internal mammary artery implants. The prognosis for patients with sternal wound infections appears related to the length of time required for institution of treatment and the adequacy of initial therapy. Most of these infections are caused by Staphylococcus, although the more complicated infections often are caused by fungi. The prevention of serious sternal infections depends on a combination of proper preoperative preparation, attention to minute details at the time of operation and recognition of variables predisposing to wound complications.