The left sternothyroid muscle was not found during routine educational dissection of a 54-year-old female cadaver. While many variations of the infrahyoid muscles exist, few cases of absent sternothyroid muscles have been described in the literature. In this instance, the unilateral absence of the sternothyroid muscle is believed to be congenital as the regional anatomy of the neck was otherwise unremarkable and signs of surgery or trauma were not present. The exact functional implications, if any, due to the absence of the left sternothyroid muscle are not known.