The sternomastoid "tumor" of infancy is a firm, fibrous mass, appearing at two to three weeks of age. It may or may not be associated with torticollis. Generally, the "tumor" initially grows, then stabilizes, and in about half the cases recedes spontaneously after a few months. It may leave a residual torticollis or may be associated with a facial or cranial asymmetry of a delayed torticollis. The etiology is unknown, a direct cause and effect relationship to birth trauma has been largely disproved although approximately half these children are products of breech deliveries. The treatment is controversial. Approximately half of these "tumors" will resolve spontaneously without sequelae. Progressive torticollis or development of facial asymmetry are considered indications for surgery. The purpose of this report is to acquaint the head and neck surgeon with this entity which may confront him for diagnosis and treatment.