The use of the internal mammary artery for revascularization of the coronary arteries has expanded over the last years. In a series of 250 consecutive coronary artery revascularizations, there was at least 1 internal mammary-coronary artery anastomosis in 222 patients (89%) and multiple internal mammary-coronary artery anastomoses were performed in 77 patients (31%). During the revascularization procedure, weaning from cardiopulmonary bypass was not possible in 4 patients with internal mammary-coronary artery anastomoses. These 4 patients showed signs of left ventricular failure, and additional saphenous vein bypass to the left anterior descending coronary artery, already revascularized by the left internal mammary artery, was performed. Weaning from cardiopulmonary bypass was then possible in 3 out of 4 patients. Thus, in some patients (1.2%), internal mammary-coronary artery anastomoses provide inadequate nutritional support for the myocardium.