All cases of thyroid cancer reported to the Finnish Cancer Registry in 1958-62 were re-examined histologically; 227 cases of thyroid carcinoma were found. The correlation between survival rates and different histologic and clinical features was studied. The survival rates for papillary carcinoma were significantly higher than those for follicular carcinoma, and the latter significantly higher than those for anaplastic carcinoma. The survival rates for medullary carcinoma were similar to those for papillary carcinoma, but there were only 10 medullary tumors. Within papillary carcinoma, vascular invasion correlated with low survival rates. In follicular carcinoma, the encapsulated type, and in anaplastic carcinoma the diffuse small cell type had higher survival rates than other tumors. The extent of the primary tumor and the presence of distant metastases correlated with survival, but the presence of regional metastases did not. The presence of severe compression symptoms correlated with low survival rates. Young patients and females had higher survival rates than old patients and males. In making a postoperative estimation of prognosis it is best to take the histologic type, the extent of the primary tumor, and the presence of distant metastases into consideration. A tentative preoperative prognosis can be bases on the age and sex of the patient and the presence of distant metastases and severe compression symptoms.