Never before has the handwritten legacy of Grigory Rasputin become the subject of scientific scrutiny. This gap is explained by the fact that Rasputin’s manuscripts has never been separated from the surviving corpus of his texts, which were published only partially and without appropriate textual preparation. Therefore, the author tried to compile a complete corpus of Rasputin’s manuscripts found in the archives and museums of Russia as well as from the rest of the world. This exercise enabled him to identify and record the main linguistic and archaeographic characteristics of Rasputin’s manuscript heritage. The process of compiling a corpora of manuscripts of an individual author and its subsequent critical examination naturally and inevitably leads to the isolation of a number of manuscripts from this corpus for reasons of their inconsistency with the characteristics found in the main body of manuscripts. The recent study of the corpus of Grigory Rasputin’s manuscripts revealed that a number of his newly discovered letters and notes turned out to be alien. It is evident that the accuracy of the conclusions drawn from the examination of written monuments directly depends on the expert’s familiarity with the reference samples in the original. But since the corpus of Rasputin’s manuscripts had not previously been formed, the examination was carried using reproductions, and without a deep source study or linguistic analysis of the manuscripts. This inevitably led to erroneous conclusions, in particular, to the recognition of secondary manuscripts as Rasputin’s originals. To confirm his theses, the author carries out a detailed examination of five manuscripts that have been identified in recent years and have been recognized by experts as originals. The main, but not the only argument with which the author tries to refute the conclusions of experts, is a linguistic analysis. The linguistic characteristics of Grigory Rasputin’s idiom provide us with the main criterion according to which one can reach a verdict on the authenticity of a particular manuscript authored by this historical figure.