The intra-aortic balloon pump (IABP) is a mechanical device designed to support the failing or ischaemic myocardium. It is usually inserted percutaneously through the femoral arteries, with the tip just distal to the left subclavian artery. The principle lies in diastolic counterpulsation (augmentation) that inflates at the start of diastole and deflates just before systole. This allows increased coronary perfusion during diastole and also reduces the impedance to forward flow during systole. This scenario of reduced cardiac workload and increased supply of oxygen results in increased cardiac output. Indications include mechanical complications of myocardial infarction, refractory unstable angina, high-risk cardiac surgery, and support of the failing myocardium before transplantation. Contraindications include aortic dissection, aortic regurgitation and severe peripheral vascular disease.