The article is devoted to the autograph as a genre of natural writing speech. The object of researcher’s attention is presented by memorable inscriptions (signatures), handwritten by authors on fiction books. Texts-autographs are realized through natural written activity of a person, possess typical features peculiar to genres of natural written speech in general (according to N.B. Lebedeva’s classification). It allows to relate autograph to this particular type of genres. The leading genre-formative parameter of texts-autographs is their manuscript nature. Analysis of the material showed that the autograph has a number of features related to the language realization, structure and style of writing typical for genres of natural written speech (unofficiality, spontaneity, subordination to «natural laws» and «alive features»). Texts-autographs have explicitly expression of address orientation. This fact brings texts of this genre closer to letter, note and some others. The autograph is a creolized text because author’s text on the fiction editions is perceived in close connection with the title page of the book, and text of autograph sometimes has a semantic linkage to the title of the work. In addition, the autograph is not only a unique documentary source, but also the reproducer of some author’s emotional experiences. Texts-autographs contain such characteristic features as ease, immediacy and inseparability of the text’s inclusion into psychological and social author’s space, that is, in his everyday existence.