Abstract: The extracorporeal circulation apparatus in accordance with the invention comprises a plurality of pneumatic diaphragm pumps incorporated in parallel relationship in a single fluid-flow system of extracorporeal blood perfusion.The electronic control system of the arrangement which processes the EKG signals is provided with a control signal distributor for sequential pump actuation such that the priming time of each pump is prolonged, frothing and haemolysis of the blood is prevented, and the stroke volume of the apparatus is maintained at a predetermined level.