A histopathologic study was made on 1,095 thyroid specimens which had been removed surgically under various diagnoses at Seoul National University Hospital during the six-year period, 1976-1981. Among the 1,095 surgically removed thyroids, adenomatous goiter was the most common single disease, accounting for 43% of all cases; this was followed by papillary carcinoma and follicular adenoma. Of the malignant tumors, papillary carcinoma was the most frequent, accounting for 259 cases, 76.85% of all malignancies. Ground glass nuclei and psammoma bodies were seen in approximately 64% and 65% of the papillary carcinomas, respectively. Squamous metaplasia was, however, present in 17%. There were also 53 follicular, 13 anaplastic and seven medullary carcinomas. Of the 56 occult sclerosing carcinomas, most were detected in the backgrounds of the adenomatous goiters. Occult sclerosing carcinoma was found in 9.2% of the adenomatous goiters and in 4.3% of the follicular adenomas.