ВСТУПИТ. СТАТЬЯ, ПЕРЕВОД С ПОЛЬСК. И КОММ. С. Л. КУЗЬМИНА, Л. Ю. РЕЙТА We analyze historical reliability of the F.A. Ossendowski book "Beasts, Men and Gods" in the context of new data from archives, memoirs and two unpublished manuscripts by Ossendowski. Data on his contacts with baron R.F. von Ungern-Sternberg, as well as on events in the Western and the Central Mongolia are mainly reliable. Dating from the author's arrival to Uliassutai to departure from Mongolia is generally correct. Inconsistencies in his famous book are discussed in detail. Following inconsistencies are most important. Ossendowski's travel to Tibet and his conversations with Bogd-gegeen VI// should be considered as fantasy. Stories on Tushegoun-Lama (Ja-Lama) do not withstand verification. Data on Bogd-gegeen and Buddhism contain significant inconsistencies. Agharti and the King of the World represent Ossendowski's theosophical treatment of religious stories, mainly on Shambhala. Part of adventures and battles can not be proved but these data have no historical value. Notebook (apparently, the diary) of Ossendowski's travel in Mongolia, as well as his report on political situation there in March-April 1921 are first published (Russian translation).