The book “Mysteries of the Fly Agaric” is a scientific study of the role of the red fly agaric in the mythology and ritual practice of shamans of Siberia and the Far North. Previously, this topic did not receive enough attention from specialists, and now this gap has been filled. The material for the book was collected by the author over many years and included virtually all known folklore and ethnographic data on this issue, as well as his own field research. The myths about the creation of the world are analyzed in detail, where Fly Agaric is created one of the first to protect the earth from evil spirits; the legends about fly agaric girls are considered - forest beauties who lure a traveler to their country; There are numerous stories about the travels of shamans into the otherworldly realms of hidden areas of consciousness. An analysis of the stages of intoxication with the mushroom and a description of the methods of its use in folk medicine are also done. The author does not encourage the use of prohibited psychoactive substances! His work is purely ethnographic and cannot be considered either directly or indirectly as the popularization of narcotic drugs! Drug use outside the historically established culture and rituals causes addiction and leads to premature death! This is very dangerous! The publishing layout is saved in PDF A4 format.