Book by the outstanding Russian historian A.A. Zimin (1920–1980) “The Oprichnina of Ivan the Terrible,” published in the first edition in 1964, is the only chronologically organized and systematized account of the events of one of the darkest eras in the history of medieval Rus', which immediately took its place among the classic works about the past of Russia. Second edition of the book , which received the author’s name “Oprichnina,” was conceived immediately after the first. Until his death in 1980, A.A. Zimin supplemented the text with new materials and considerations, clarified the assessments and improved the concept of this terrible and mysterious period. All author’s additions and changes were made by A.L. Khoroshkevich with the participation of V.G. Zimina.