Objective: Polytraumatized patients present with defects of haemostasis that manifest clinically either by haemorrhage and/or thrombosis. During the initial, as well as during the later phases of treatment, clinicians should take into account the most recent developments in the understanding, in the evaluation of the risk, and in the prevention of haemorrhagic and thrombotic complications., Source: A group of experts, convened by the "Groupe d'intérêt en hémostase périopératoire" (Perioperative Haemostasis Interest Group) during the Annual Meeting of the Association of Anaesthetists of Quebec, held a symposium to review and integrate recent developments on haemostatic complications associated with trauma., Main Findings: The normal haemostatic balance is strongly compromised by trauma and shock. The percentage of patients with a coagulopathy and surgically uncontrollable haemorrhage varies between 18 and 40%. Abnormal coagulation after trauma is of multifactorial origin. Coagulopathy secondary to haemodilution is no longer considered the main cause of haemorrhage. Disseminated intravascular coagulation (DIC) is often manifest in the traumatic context. One out of every three polytraumatized patient will develop a deep vein thrombosis despite the preventive measures available at present. Clinical or laboratory detection of venous thrombosis either lacks sensitivity (physical examination or ultrasonography), or cannot be performed serially (phlebography)., Conclusions: Prevention and treatment of disorders of haemostasis relies upon the rapid and effective treatment of shock associated with trauma. Prevention of thromboembolic complications is paramount, taking into account the evolving balance between the risk of haemorrhage and the risk of thrombosis.