Presented here are the results for clinical study on 65 cases of simple goiter the author treated during the period of 4 years and 10 months from jan. 1963 throught Oct. 1967 at the Seoul National University Hospital and Han-Il Hospital. It has been customary to classify simple goiter, according to the gross morphological characteristics of the thyroid gland, as diffuse and nodular type. This paper attempts to investigate the histopathological changes and treatment of simple goiter respectively. Sixty five cases of simple goiter were classified into 4 types; namely degenerative type was 20 cass (30.8%), proliferative type was 7 cases (10.8%), colloidal type was 24 cases (36.9%0 and cyst formation with degeneration was 14 cases (21.5%), on the basis of histopathological findings. Thus, it is essential that simple goiter should be differentiated from thyroid tumors as soon as practicable. The effectiveness of medical treatment with desicated thyroid and autohemotherapy for certain simple goiter are also discussed.