The radioisotopic scanning of the thyroid gland is well established method of demonstrating morphology of thethyroid gland and is used to measure the size, area and weight of thyroid gland. The purpose of this investigationis to observe the various effects of goiter to the regional trachea. Both radioisotopic scanning and roentgenogramwere taken at the same time to evaluate size, area and weight of the thyroid glands, as well as to measure thewidth of soft tissue structure of the neck and the regional trachea in normal and goitrous patients. The clinicalmaterials consisted of normal thyroid group for control (46 cases), diffuse simple goiter group (76 cases) andGraves's disease group (59 cases). The results were as follows; 1. The goiter causes some narrwoing of theregional trachea to various degree which is not necessarily reflective of the size of goiter. 2. The goiter mayincrease the width of retrotracheal soft tissue space. 3. The lateral roentgenogram of the neck appear very usefulin estimating the thyroid gland three dimensionally and the effect of goiter to the regional trachea.