This paper is historical in character, with interpretations and corrections, bringing the work of many scientists of this and other countries for the past 50 years into one complete whole, into an understandable bit of medical history. Endemic goiter is one of the oldest diseases known, and, in addition to the methods of treatment by the Ancient Greeks, there have been during the past 3 centuries repeated contributions to the growing knowledge of endemic goiter. The prevention of endemic goiter in man, as it is known today throughout the world, is based entirely on the findings and teaching of David Marine. His investigations were started in 1905 at Western Reserve University. The first report on the study of the Relation of Iodine to the Structure of the Thyroid Gland was published in 1908 by Marine and Williams. 1 The next publication in 1909 was by Marine and Lenhart on the