The preferred treatment for patients with multifocal thyroid carcinoma or a single focus of malignancy larger than 1.5 cm is near-total thyroidectomy followed by radioiodine ablation therapy of the remaining thyroid tissue. The authors describe a patient who had a 2.6-cm papillary thyroid carcinoma but no evidence of metastatic disease. This malignancy was not diagnosed during intraoperative frozen section examination, but rather at the final pathologic analysis. The unilateral thyroid lobectomy resulted in a recurrent laryngeal nerve palsy. During subsequent I-131 therapy of the remaining lobe, features of acute radiation thyroiditis, including thyrotoxicosis, developed.