Haemostasis is the normal physiological response that prevents significant blood loss after vascular injury. The process depends on an intricate series of events involving platelets, other cells and the activation of specific blood proteins, known as coagulation factors. When blood vessel injury occurs, physiological haemostasis is triggered and the coagulation process occurs. Haemostasis serves to maintain the integrity of the circulatory system; however the process can become imbalanced, leading to significant morbidity and mortality. Knowledge of the process of haemostasis is therefore important in order to understand the major disease states associated with thrombosis.