Patients with a clinically concerning dominant thyroid nodule have been managed by lobectomy or total thyroidectomy at our institution. We determined the complications associated with both approaches and the ability of thyroid lobectomy to avoid the need for thyroid hormone replacement therapy. Records of all patients with a dominant thyroid nodule managed with surgery from August 1993 through December 2000 were reviewed for demographics, history of head and neck radiation, indication for surgery, preoperative fine-needle aspirate results, final pathologic evaluation, perioperative complications, determinations of need for subsequent thyroid surgery after lobectomy, and need for thyroid hormone replacement therapy after surgery. Patients with a preoperative diagnosis of malignancy or bilateral or diffuse disease were excluded because these conditions would uniformly be managed by bilateral thyroidectomy. The complications for the lobectomy group (n = 131) compared with the total thyroidectomy group (n = 84) were: recurrent laryngeal nerve paresis (4.6% vs 2.4%), recurrent laryngeal nerve injury (0.8% vs 0), and transient hypoparathyroidism (1.5% vs 9.5%; P = 0.007). No permanent hypoparathyroidism was identified in either group. Postoperative thyroid hormone replacement was required in 64 of 131 lobectomy patients (48.8%). Complications associated with either surgery were low. Total thyroidectomy was not associated with clinically significant additive morbidity. Patients treated by lobectomy should be aware of a nearly 50 per cent chance of requiring thyroid hormone replacement. Total thyroidectomy avoids future thyroid surgery; lobectomy patients remain at risk. When complications can be minimized total thyroidectomy should be considered an option in the management for patients with dominant thyroid nodules that require surgery.