A selected group of 213 men who had worked at Chernobyl Atomic Power Station within 1986-1987 during 7-60 days (average index is 30+10.4 days) was examined. Mental disorders were found in 196 patients (asthenic, dysthymic, psychovegetative, psychoorganic syndromes). Various neurological symptoms, for example of Marinesku-Rodovichi, were often met. Angiopathia of the retina among 61.7% was found and discircular encephalopathia among 39.3% cases was discovered. The latter suggested by the obtained instrumental data (REG, EEG, SPECT). The author considered aetiology of these disorders, demonstrated scientific value of studying Chernobyl liquidators cohort, as they were protected from internal radiation and reside on radiation “pure” territories. External radiation dose in those liquidators was 18.7+10.8 cGrey. Catamnesis enabled to doubt “radiation aetiology” of all syndromes revealed by clinical and instrumental studies. So, the prolonged over 1-2 months external radiation of such low doses could not case health deterioration in adult males. The MMPI-test profile of our liquidators was very similar to the MMPI-test of american veterans of Vientam war. Diagnosed psychoorganic syndrome in 53.6% cases could have alcohol aetiology. This conclusion is not extrapolated to the whole Chernobyl liquidators cohort. Also the author disputed with psychiatrist V.A.Soldatkin about situation in Rostov-on-the-Don region, with psychiatrists V.L.Malygin, B.D.Tsygankov about situation in Tula region, with psychiatrists V.A.Buikov, P.P.Balashov on the aetiology of psychopathology among the population of South Urals region (after radioactive incidents). The influence of the low doses of the gamma-radiation, of the Post-Traumatic Stress Disorders, of the Alcohol abuse et cetera was discussed.