The epidemiological data of thyroid carcinoma are difficult to evaluate. Several variables influence the biologic behaviour and the great number of occult papillary carcinomas obscure the picture. Among our 1116 patients we found as first symptoms solitary nodules in 41,4% being localized in differentiated carcinomas significantly more frequently in the right than is the left lobe. Multinodular goiter was seen in 24,2%, cervical lymph nodes in 10,9% and distant metastases in 3,2%. In medullary carcinoma cervical lymph nodes were seen in 27% and thus the second most frequent leading symptom. Together with sonography, thyroid scan and fine needle biopsy it is possible today to assure preoperatively at a high degree the diagnosis. A differentiated therapy is generally applied taking into account the particular prognosis of the patient, especially in papillary carcinoma. A more radical initial treatment is necessary in follicular carcinoma. In medullary carcinoma only the thyroidectomy without radiation has been proven as effective means.