Abstract: The symptoms and signs in 40 cases of congenital abnormalities of foramen magnum's region have been analysed. 26 cases presented with dezziness and unepuilibrium, among whom, 16 had spontaneous nystagmus. ENG investigation was made systematically in six cases with spontanous and gaze nystagmus, ocular nystagmus, dysmetria, decreased intensity of optokinetic nystagmus, abnormat smooth pursuit movement and failure of fixation suppression. Causes of the abnormalities were reviewed. The etiology and pathophysiclogical bases for the changes in ENG are briefly discussed also.