['To identify any risk factors for incidental parathyroidectomy and to define its association with symptomatic postoperative hypocalcemia.', 'Retrospective study.', 'Tertiary referral cancer center.', 'Consecutive patients who underwent thyroid surgery between 1991 and 1999. Patients who underwent procedures for locally advanced thyroid cancer requiring laryngectomy, tracheal resection, or esophagectomy were excluded.', 'All pathology reports were reviewed for the presence of any parathyroid tissue in the resected specimen. Slides were reviewed, and information regarding patient demographics, diagnosis, operative details, and postoperative complications was collected.', 'Identification of parathyroid tissue in resected specimens and postoperative symptomatic hypocalcemia.', 'A total of 141 thyroid procedures were performed: 69 total thyroidectomies (49%) and 72 total thyroid lobectomies (51%). The findings were benign in 68 cases (48%) and malignant in 73 cases (52%). In the entire series, incidental parathyroidectomy was found in 21 cases (15%). Parathyroid tissue was found in intrathyroidal (50%), extracapsular (31%), and central node compartment (19%) sites. The performance of a concomitant modified radical neck dissection was associated with an increased risk of unplanned parathyroidectomy (P =.05). There was no association of incidental parathyroidectomy with postoperative hypocalcemia (P =.99). Multivariate analysis identified total thyroidectomy as a risk factor for postoperative hypocalcemia (P =.008). In the entire study group, transient symptomatic hypocalcemia occurred in 9 patients (6%), and permanent hypocalcemia occurred in 1 patient who underwent a total thyroidectomy and concomitant neck dissection.'] Does incidental parathyroidectomy during thyroid surgery cause transient symptomatic hypocalcemia?