Ischaemia-reperfusion injury is the mechanism underlying (partial) flap loss. This is not only a traumatic event for the patient, it also causes increased patient morbidity [Kerrigan CL, Stotland MA. Ischemia reperfusion injury: a review. Microsurgery 1993;14:165-75] as well as prolonged hospitalisation, increasing medical consumption and costs. For surgeons who perform flap surgery, it is important to have knowledge of ischaemia-reperfusion injury in order to prevent it. In this article, an update on the recent research on ischaemia-reperfusion is given. The production of reactive oxygen species, neutrophil influx, depletion of NO and apoptosis are discussed as well.