Objective. To evaluate the effect of modified therapy on the course of epilepsy in patients with the low cerebral-spinal-fluid-cranial (CSF-cranial) index. Material and methods. One hundred and twenty-four patients with cryptogenic epilepsy were prospectively analyzed. Group I consisted of 36 patients with a normal volume of reserve cerebrospinal fluid and a level of the CSF-cranial index within the physiological norm (from 1.2 to 3.6), who received standard therapy. Group II consisted of 42 patients with a small volume of reserve cerebrospinal fluid spaces and a CSF-cranial index lower than the physiological norm (from 0.8 to 1.2), who received standard therapy. Group III (n=46) was characterized by a small volume of reserve cerebrospinal spaces and a CSF-cranial index lower than the physiological norm. Patients of this group received modified therapy. Results and conclusion. Normalization of the level of intracranial pressure in patients with a low cerebrovascular index reduced the frequency of epileptic seizures. After one year follow-up, the proportion of patients with very frequent seizures decreased by 25.3%, with frequent seizures by 23.9%, after 2 years by another 33.1 and 15.7%, respectively. A correlation was found between the frequency of seizures and the level of intracranial pressure (G=0.24, p=0.043).