One hundred and eighty-seven patients with different stages of cerebrovascular insufficiency (CI) have been examined. A diagnosis of CI was based on the results of neurological and neuropsychological study, ultrasonic dopplerography, rheo- and encephalography, electrocardiography, brain MRI and eyegrounds examination. Neurological scales were used for neurological status assessment and further data processing. The study aimed at evaluation of tolerability and clinical efficacy of the medication and complications in CI course. Semax treatment resulted in significant clinical improvement, stabilization of the disease progress and reduced a risk of stroke and transitory ischemic attacks in the disease course. The drug is featured by minor percent of side-effects and is well tolerated by patients, including those of older age groups.