Understanding of blood coagulation has evolved significantly in recent years. Both newcoagulation proteins and inhibitors have been found and new interactions amongpreviously known components of the coagulation system have been discovered. Thisincreased knowledge has led to the development of various new diagnostic coagulationtests and promising antithrombotic and haemostatic drugs. Several such agents arecurrently being introduced into clinical medicine for both the treatment and prophylaxis ofthromboembolic disease and for the treatment of bleeding. This review aims to elucidatethese new concepts and to outline some consequences for clinical anesthesia andperioperativemedicine.