Several studies have reported hemostatic abnormalities, both in terms of bleeding or thrombosis, in patients with various thyroid dysfunctions. The aim of this review is to briefly discuss the relationship between thyroid disorders and hemostasis (i.e. primary hemostasis, coagulation factors and fibrinolytic system). From the analysis of the more recent literature data, it appears evident that most of the coagulation abnormalities associated with thyroid disorders are a consequence of a direct action of thyroid hormones on the synthesis of various hemostatic factors or a derangement of immune function. On the whole, these data suggest that a hypercoagulable state is present in hyperthyroid patients, while patients suffering from moderate hypothyroidism are at increased risk of thrombosis contrasting with the bleeding tendency of those presenting severe hypothyroidism.