Completion thyroidectomy (cT) is sometimes necessary after thyroid lobectomy (TL), and it remains controversial whether 2-stage thyroidectomy adds operative risk. This study compares complication rates for TL, total thyroidectomy (TT), and cT.Using a cohort design, we reviewed 100 consecutive cases each of TL, TT, and cT. Complications examined included reoperation for hematoma, temporary/permanent recurrent laryngeal nerve (RLN) dysfunction, and hypoparathyroidism.Two patients had reoperation for hematoma, both in the TT cohort (p = 0.33). No patients in any cohort had permanent hypoparathyroidism or RLN injury, but transient RLN paresis occurred in three (3%) TL, two (2%) TT, and no (0%) cT patients (p = 0.38). Transient hypoparathyroidism occurred in 3% following TT versus 0% after cT (p = 0.12). Overall complication rate was higher after TT (7%) compared to TL (3%) and cT (0%, p = 0.02).At a high-volume center, the observed complication rates were equivalently low for TL, TT, and cT.Completion thyroidectomy is occasionally needed after lobectomy, but its procedure-specific risks are not well characterized. In a cohort study at a high-volume center, operative outcomes for patients undergoing thyroid lobectomy, total thyroidectomy, and completion thyroidectomy were compared and equivalently low complication rates were observed for all 3 procedures.