The last part of the 19th century was a period of great achievements in medicine and endocrinology. The thyroid gland evolved from being considered a rudimentary structure to an organ related to specific diseases. The singular importance of iodine became acknowledged. Graves-Basedow's disease was described. Surgical treatment evolved with extraordinary speed. Theodor Kocher observed that the clinical picture in patients after total thyroidectomy was similar to the one seen in cretinism. In 1850, the first case of hypothyroidism or myxedema was described. Less than 50 years later, effective treatment was introduced. Another 50 years later, autoimmune thyroiditis was ascertained as the most frequent cause of hypothyroidism (in areas with no iodine deficiency). This paper gives a short survey of the history of hypothyroidism and its treatment.