Infantile fibromatosis is a rare entity in children. Although the cervical region is one of the frequent sites of location for this tumor, the diagnosis may be delayed if it occurs in a usual location for a well-known entity, such as muscular torticollis or fibromatosis colli. The authors present an infant with infantile desmoid fibromatosis of the sternocleidomastoid muscle, which has been considered initially as olive of muscular torticollis.