BASIC and essential to reliable understanding of the disorders of anybodily organ or system is thorough knowledge of the minute gross and histologic anatomic characteristics of that organ. The pathologic findings observed must then be correlated with clinical observations under various circumstances of health, physiologic alterations and pathologic deviations. In reference to the thyroid gland, such basic pathologic data have been rather slow to accumulate because often the routine necropsy does not include removal of the entire gland. Even when the thyroid is removed, a systematic, minute study of the gland is rarely undertaken as part of the routine examination if the gland appears normal externally or when bisected. In order, then, to obtain additional basic pathologic data concerning the thyroid gland, the following study was undertaken. The thyroid gland was removed en toto from each of 1,000 subjects undergoing routine consecutive postmortem examination in the Section of Pathologic Anatomy of the Mayo Clinic from July 1, 1951 through June 30, 1953.