Clinical follow-up of 9 patients with agenesis of the corpus callosum is analysed. It is established that the pleomorphism of the clinical manifestations in agenesis of the corpus callosum is determined by the concomitant cerebral lesions. Pneumoencephalography should be considered the method of choice in the diagnosis of agenesis of the corpus callosum because it demonstrates the changes in the ventricular system characteristic of this anomaly and the changes in the cerebrospinal fluid channels attendant to it. A decrease in the distance between the inferior sagittal sinus and the internal cerebral vein and in the distance between the pericallosum artery and the internal cerebral vein are pathognomonic angiographic signs. No pathognomonic changes in the bioelectric activity of the brain in agenesis of the corpus callosum were detected.