The Riedel's thyroiditis, also called "wood's thyroiditis", is a rare chronic "inflammatory" disease of unknown etiology, relatively frequent in female >45-50 years, characterized by a fibrotic process that pervades thyroid and neighbouring structures (vessels, muscles, oesophagus, trachea upper- mediastinum). The authors discuss about three cases of Riedel's thyroiditis and report the outcome after total thyroidectomy in two cases and sub-total resection in the other one.