In 1964, the events of haemostasis were organized into the intrinsic and extrinsic pathways by the cascade/waterfall hypothesis, with primary physiological importance being given to the intrinsic pathway. Recent experimental evidence, as well as information about the clinical course of patients with various coagulation factor deficiencies, indicates a more prominent role for tissue factor. Rediscovery of the plasma protease inhibitor, tissue factor pathway inhibitor, and new information about the activation of factor XI have supported a revised theory of coagulation.