Intermittent pneumatic compression (IPC) is a widely used and recommended method to prevent deep vein thrombosis. While the haemodynamic effects of IPC are well understood, the objective of this systematic review was to analyse the evidence for additional haematological changes. Forty-eight studies were identified where the haematological effects of IPC were measured. The many differences between the studies prevented meta-analysis, but there was a significant amount of evidence that global fibrinolytic activity was increased by IPC, and that levels of D-dimer and tissue factor pathway inhibitor in the blood also increased. There was less consistent evidence for changes in tissue plasminogen activator, plasminogen activator inhibitor and other fibrinolytic parameters. The evidence for changes in pro-coagulant factors and many measures of platelet activation was weak, but there was evidence for increases in prostacyclin. There is sufficient evidence to conclude that IPC does produce haematological changes, but not enough data to clarify the detail of those changes or to determine if it is mediated more by direct compression of the blood vessels, or by the flow changes.Georg Thieme Verlag KG Stuttgart · New York.