Records of 139 patients with pure follicular thyroid carcinoma were reviewed and correlations between survival rate, extent of tumor, surgical and radioiodine therapy were investigated. The survival rate at 10 years was good for younger patients (80% under 40 years of age) and without metastases (90%), but the prognosis was much less favorable for older patients (40% above 40 years of age) and subjects with distant metastases (20%), even if with radioiodine uptake. Diagnostic methods together with surgical and radiometabolic therapy are discussed. Since extensive histologic invasion of the capsule and blood vessels appeared to be associated with an increase in recurrence rate, the authors underline that radioiodine therapy is indicated in all these patients. Moreover they suggest its use also in less invasive follicular carcinoma.