We describe a cervical sympathetic chain schwannoma in a 77-year-old woman who presented with a neck mass and Horner's syndrome. Such schwannomas are rare and this is the first documented case of a Horner's syndrome at presentation. The mass was excised via a cervical approach and her post-operative course was uneventful. The prognosis is excellent, with recurrence being rare. A brief discussion of the pathology, presentation, diagnosis, and treatment of this condition is made in this paper. The relevance of the uncertainty in diagnosis is discussed with the message that a pre-operative Homer's syndrome may guide the surgeon in the care of the patient but we suggest that in all cases proper counselling of the possible neurological consequences of this surgery be conducted.