Blood coagulation is the result of a complex cascade of proteases that produce an insoluble fibrin polymer from soluble fibrinogen. Abnormal or excessive coagulation can cause venous thromboembolic disorders or arterial thromboembolic disease. Parenteral and oral anticoagulants have demonstrated efficacy in treating these conditions. Haemorrhage is a predicable consequence of anticoagulant poisoning. Treatment involves the general management of haemorrhage, and the administration of specific antidotes for individual anticoagulants are discussed.