Ninety-four patients with tick hyperkinesis (57) and Tourette's syndrome (37) were studied. Neuropsychological examination revealed memory, attention and audio-motor disturbances and symptoms of dysgraphia and dyslexia. Cognitive impairment may develop before ticks appearance and aggravate during hyperkinesis exacerbation. In the patients with Tourette's syndrome, cortical dysfunctions were mostly pronounced. These cognitive disturbances correlated with the indices of spectral analysis of bioelectrical brain activity in frontal and temporal areas. In 83 patients, an efficacy of encephabol treatment combined with basic therapy was studied. Encephabol given in dosage 200-300 mg daily to patients aged 5-7 years and 600 mg--to those aged over 7 years during 6 weeks significantly improved memory, attention and praxis function.