Laryngeal cysts of thyroid cartilage origin are unusually rare. A patient had a degenerative cyst of the thyroid cartilage. This presented as a unilateral false cord swelling. Computed tomography helped to localize the lesion to the left thyroid ala. An external laryngeal approach was used for excisional biopsy, and this also proved to be curative. The cyst probably resulted from a traumatic episode 35 years earlier.