A REVIEW of this problem, in a small general hospital, is of value because of its variance with many published reports.1 Two different groups of patients are considered. The thyroids of 155 patients were investigated because of the presence of a "single nodule," observed clinically. These patients were otherwise unselected. Also studied are 27 patients with cancer of the thyroid who have been followed for periods varying from six months to 33 years. The primary operation in the latter group was not necessarily performed by us. Concurrent diagnosis on the tissue of each patient was made by more than one pathologist. All the cancers showed blood-vessel, lymphatic, or capsular invasion, or some combination. At present the proper histopathologic categorization of cancer of the thyroid is difficult if not impossible because of the multiplicity of classifications now extant. They are the results of an attempt to render prognosis from histopathology