Haemostatic abnormalities are a common phenomenon in patients with thyroid diseases. On one hand the condition of hyperthyroidism is associated with an increased risk of thrombotic events, on the other in severe hypothyroidism can be found a haemorrhagic tendency, as opposed to the subclinical hypothyroidism seems to correlate with increased thrombotic risk. The prospective, single center, observational MITH study (Mantua Investigation on Thyroid and Haemostasis), whose results are presented, aims to evaluate coagulation parameters in patients with thyroid disease, to establish the prevalence of haemostatic abnormalities in various conditions, to analyse the implications and clinical response to therapy established.