The Hemopump^TM is a catheter-mounted mechanical circulatory assist device which can support the majority of the circulation and significantly reduce left-ventricular work. It can be introduced via a peripheral artery or the ascending aorta. The following is an overview of the operation of the Hemopump and the results of a clinical trial in which the Hemopump was used to treat cardiogenic shock. In addition, the results of pilot experiences using the Hemopump for circulatory support during aorto-coronary artery surgery and high-risk angioplasty will be discussed.