An ex-libris (a bookplate) is a valuable historical and cultural information resource. It helps to determine the ownership of a book in a particular collection, allows the understanding the history of existence of a copy that had several owners, and clarification the degree of its uniqueness. The purpose of the article is to analyze the bookplates available on the book rarities of the first quarter of the XIX century from the collection of the research library of Ulyanovsk State Pedagogical University named after I. N. Ulyanov. By means of the identification of book signs, the belonging of rare publications to private collections and the peculiarities of existence of each particular copy in the history of national culture are established. In particular, one of the books belonging to the lost Usolskaya library of count V. P. Orlov-Davydov, dispersed among the libraries of the country and reconstructed by specialists, was identified. Two other books were the part of private libraries of historical figures who were in fairly close relations with prominent figures of Russian literature (the poet M. Yu. Lermontov) and science (the inventor of radio A. S. Popov). The results of the research can expand the understanding of the uniqueness of rare copies of Russian and foreign publications from the Fund of the research library of the Ulyanovsk State Pedagogical University, such as” Selected spiritual works of Fenelon, Archbishop of Cambrai” (1820–1821), “Nouveau dictionnaire géographique universel” (New dictionary of geographical names) by Jacques McCarthy (1824) and «Histoire de France» (History of France) by Louis-Philippe Segur.