Intra-aortic balloon pumps (IABPs) are circulatory assist devices used to treat a number of cardiovascular conditions. IABPs provide temporary circulatory support by reducing the resistance to blood flow out of the heart during systole and by providing added pressure to aid in perfusing the heart during diastole. In this Evaluation, we tested three IABPs from three suppliers. We examined the units' technical performance, safety and monitoring, human factors design, transport operation, and supplier support. Rather than test all the triggering (activation) modes available, we focused our testing on the modes most commonly used on each unit. We also provide information on an IABP currently available only in Japan; although we did not test this unit, we do provide a preliminary judgment based on the information provided to us by the supplier. In the Technology Overview also included in the Evaluation, we describe the basic operation and use of an IABP, as well as review the state of the art of this technology. And in the Selection, Purchasing, and Use Guide at the conclusion of the Evaluation, we discuss such topics as balloon costs and sizing, interfacing IABPs with patient monitors, and the use of IABPs in community hospitals.