The spectrum of the cutaneous manifestations of thyroid disease includes cutaneous metastases from thyroid malignancies and thryoglossal duct cysts, nonspecific alterations of the skin, hair, and nails reflecting both the hyperthyroid and hypothyroid states, and the multiple associations of thyroid disease with other cutaneous and systemic diseases. Internists, family practitioners, pediatricians, geriatricians, and dermatologists address these issues on a daily basis: When is it appropriate to evaluate a patient for thyroid disease? How should the patients be evaluated? How often should testing be performed? Should other family members be screened for thyroid disease? The purpose of The Thyroid in Dermatology is to raise awareness of the vast spectrum of thyroid-skin interactions, and to provide a framework for the appropriate diagnosis and management of these diseases.