Clinical features of 406 patients with histologically verified thyroid carcinomas were investigated from May, 1978 to April, 1985 at the Seoul National University Hospital with the following results. 1) The incidence of thyroid cancer according to their histological classification was 79.8% of papillary carcinoma, 14.5% of follicular carcinoma, 1.5% of medullary carcinoma, 2.2% of anaplastic carcinoma, 2 cases of squamous carcinoma and 3 cases of lymphoma. 2) The age distribution showed the peak incidence in the fourth decade (25.1%), followed by the fifth and the third decade. 3) The ratio of male to female patients was 1 : 6.1. The ratio is 1 : 5.9 in papillary carcinoma and 1 : 8.8 in follicular carcinoma. 4) The mean age was 40.2 year in papillary carcinoma, 37.4 year in follicular carcinoma. 36.5 year in medullary carcinoma, 60.3 year in anaplastic carcinoma, 62.0 year in squamous carcinoma, 59.7 year in lymphoma. 5) The diameter of the thyroid masses was smaller than 1.5cm in 19.9% of the patients, from 1.5cm to 5cm in 50.5%, from 5cm to 10cm in 25.4% and larger than 10cm in 25.4%. 6) Metastasis to the regional lymph nodes at diagnosis was noted in 44.2% of total patients, and distant metastasis was 5%, and local infiltration was 44.2%. 7) The clinical staging was revealed 42.1% of the patients in stage I, 9.1% in stage II, 35.7% in stage III, 5.2% in stage IV, and 7.9% in undetermined stage.