Among 237 patients with grossly noninvasive (intrathyroidal) papillary carcinoma of the thyroid treated by surgery at the Massachusetts General Hospital and followed for a median of 14 years, no patient had tumor recurrence either in the thyroid bed or opposite lobe. There were 12 metastatic recurrences with risks of recurrence 4.0% and 6.9% at 10 years and 20 years respectively. Eight of these recurrences were restricted to cervical lymph nodes and did not herald the development of more serious recurrent disease. The remaining recurrences were lung metastases in four patients, two of whom died, accounting for the only deaths from thyroid carcinoma in this series. Factors that influenced the risk of recurrence included lymph node metastases at initial surgery, large tumor size, and to a lesser extent, male sex. The majority of patients (176) had subtotal thyroidectomies, mostly lobectomy (131 patients). There was no evidence that the 61 patients who underwent total thyroidectomy fared better than those with similar patient and tumor characteristics on whom subtotal procedures were performed. The overall findings of this study strongly support the concept that intrathyroidal thyroid carcinoma can be successfully treated by conservative surgery.