Omohyoid muscle syndrome (OMS) featuring marked omohyoid muscle bulging during swallowing, not present at rest, was first reported by R.B. Zachary in 1969. We report a case of this condition. A 41-year-old woman reporting right neck discomfort during swallowing was found to have bulging corresponding to the omohyoid muscle course, diagnosed as OMS. We excised the muscle, found to be of normal size, at the central tendon under general anesthesia. No recurrence has been seen in the 12 months post operative. Pathological findings included omohyoid muscle degeneration, hypertrophy, and atrophy. Cases reported in Japan numbered 22 since 1983, 10 of which were treated surgically and remedied satisfactorily. No common features were seen, although normal and abnormal findings were present in macroscopic and pathological intra- or postoperative examination. OMS is benign, and warrants surgery only in cases of severe subjective symptoms or at the subject's request.