The action of thyroid hormones and their role in bone and cartilage has attracted increasing attention and considerable interest over the last 30 years, leading to notable progress in understanding the consequences of thyroid diseases on skeletal metabolism. Understanding how thyroid hormones work in bone subsequently led to new insights into the relationship between the thyroid and skeletal disorders. Euthyroid status is essential for the normal bone development and maintenance. The main thyroid hormone actions in bone cells are mediated by thyroid hormone receptors (TRs). As well, also TSH receptor (TSHR) is expressed in bone, suggesting that the hypothalamic-pituitary-thyroid (HPT) axis has a substantial role in bone metabolism.