A total of 107 patients (81 males, 26 females), their age ranging between 34 to 45 years, diagnosed as having discirculatory encephalopathy with underlying cerebrasthenic syndrome, were examined. All the examinees took part in the elimination of the Chernobyl accident effects in 1986. It was found out, that cerebrasthenia which is present in the structure of all clinical variants of organic affection of the brain is the most mobile (functional) link of the morbid process when a disorder sets in rather than the failure of the organ to perform its function. It ranks among other asthenic syndromes reflecting a specific character of exogenous radiation effect on the organism, being a result of a characteristic interaction between the organism and a health hazard. Measures to dispel the asthenic component at the initial stages of development of the disorder will make for reduction or arrest of progression of organic symptomatology.