Extracorporeal mechanical assist earlier named extracorporeal circulation (ECC)) has evolved markedly over recent years. ECLS (extra corporeal life support) is employed for the management of life threatening heart or heart and lung failure, when no other treatment option is likely to be successful. Mostly it is instituted in an emergency or urgent situation after failure of other treatment modalities. ECLS is used as temporary support, usually awaiting the recovery of organs. It can also be used as a bridge to a more permanent supporting device or cardiac transplantation (bridge-to-decision-patient). ECLS is implanted in a veno-arterial configuration (either peripheral or central cannulation) for the treatment of heart failure. This is usually seen post-cardiotomy, post-heart transplant and in severe cardiac failure due to almost any other cause (e.g. cardiomyopathy, myocarditis, acute coronary syndrome with cardiogenic shock). In contrast ECMO (extracorporeal membrane oxygenation) is used for respiratory failure and usually involves peripheral cannulation using the femoral veins +/-internal jugular vein if required. The indications for ECMO are respiratory failure, most commonly due to adult respiratory distress syndrome (ARDS), as a consequence of pneumonia, trauma or primary graft failure following lung transplantation. ECLS is also used for neonatal and paediatric cardiac and respiratory support. In this review, the technical aspects of ECLS and ECMO cannulation and the different pump systems are outlined. In addition, indications, complication rates and outcomes are discussed.