Intra-aortic balloon conterpulsation (IABP) was used to assist 109 patients with extensive myocardial infarcts, unstable angina, cardiogenic shock, and unstable cardiodynamic states after cardiopulmonary bypass over a six year period. Severe vascular occlusion occurred in three patients (3%) which required an above the knee amputation. Each patient had a long history of smoking. Obesity, atherosclerotic disease of the femoral vessels, and extensive coronary artery disease were additional contributing factors. Two of the three patients survived, but both survivors had extensive postoperative myocardial infarctions. A low flow cardiac state and the presence of atherosclerotic changes in the legs must be precipitating factors for the vascular complications. Several possible methods to minimize complications of this nature include 1) angiographic examination of the lower aorta and femoral arteries at the time of cardiac catheterization, 2) frequent monitoring with ultrasound equipment, and 3) use of anticoagulation during and after the period of counterpulsation.