Division of the lateral thyroid ligament is essential for total thyroid lobectomy. The exact extent of this ligament, first described by Berry in 1888, was studied in a series of 25 cadaveric and post-mortem subjects. The ligament was attached to the inferior margin of the cornu of the cricoid cartilage, near its pole, and extended infero-medially onto the tracheal wall, reaching the midline in 4 of the 50 lobes examined. At the level of the cricoid cartilage, the mean distance between the attachment of the ligament to the cricoid cartilage and the recurrent laryngeal nerve (RLN) entry point into the larynx was 1.9 mm. This region corresponds to the area where RLNs are mostly injured during thyroid surgery. Awareness of the extent of this ligament and the proximity of the RLN to it should lessen the risk of injury to the RLN during thyroid lobectomy and total thyroidectomy.