Based on clinical analysis, neuropsychological symptoms and electrophysiological parameters were studied the dynamics of cognitive - affective disorders in children with cerebellar tumors after surgical treatment. Special studies, in which were included 36 children with cerebellar tumors after surgery and their results, revealed the presence of cognitive impairment in all studied with a wide range of manifestations (preclinical, abortive, neurotic, autistic, verbal, sometimes reaching levels of psychotic disorders) many of them in the late postoperative period does not diminish, but on the contrary it emphasize. The phenomenon of postoperative worsening of cognitive functions in children with cerebellar tumors have certain characteristics depending on the damaged of structures of the cerebellum. Changes in CNV (contingent negative variation) and the potential of P300 may serve as indicators for assessing the degree of disturbance of cognitive functions and effectiveness of their correction as a result of treatment.