A clinicopathologic study of 241 cases of papillary thyroid carcinoma treated at the University of Florence Medical School, Florence, Italy is presented. The features of greatest prognostic value were patient's age at presentation, small tumor size, total encapsulation, extrathyroid extension, multicentricity, and presence of distant metastases. The prognosis of the disease was not influenced by the pattern of tumor growth, presence of solid areas, initial presence or subsequent development of cervical lymph node metastases, type of initial thyroid operation, performance of neck dissection, or prophylactic administration of radioactive iodine. It is concluded that conservative thyroid surgery in the form of lobectomy, without neck dissection or prophylactic administration of iodine 131 (131I), constitutes adequate therapy for most cases of papillary thyroid carcinoma. More extensive therapy should be considered for older patients and for those in whom the tumor exhibits extrathyroid extension or easily detectable multicentricity.