The embryological, clinical and radiological features of an abnormal stylohyoid chain ossification is reviewed. The common embryological origin of the styloid apophysis, the styloid ligament and the lesser cornu of the hyoid bone allows the concept of a stylohyoid entity. The pathogenesis of the ossification of the stylohyoid chain enables us to distinguish Eagle's syndrome, the stylohyoid syndrome and the pseudo-stylohyoid syndrome. The choice between medical and surgical treatment particularly surgery by external approach, is discussed.