The memorial book collection of the City and University Library in Osijek is a special collection within the library holdings which comprises materials published before 1945. The collection is divided into several subcollections: books published before 1945, the rare book collection, the Divaldiana, and the legacy collections (Hengl, Sonnenfeld, Pollak, Magjer, Rakoš, Pinterović, Kocijan, Gottschalk). This paper presents briefly the various collections and their cultural and historical values important for the local community. The memorial book collection with its completely or partially catalogued resources is available to the public. It is necessary to expertly catalog and process the collection and all its subccollections, present the collection’s structure (topics, languages, publication types), and single out old and particularly valuable books. The goal is to preserve the integrity and particularity of the subcollections. In order to provide greater public access to cultural heritage resources, the project of digitization the memorial collection was started, with a particular emphasis on the local monographies and periodicals, as well as graphic maps with local themes. Cataloging, protection, conservation and presentation of memorial collections are necessary in order to preserve them as part of the cultural and social identity and heritage. Thus the library has a significant role in contributing to the preservation of the memorial and cultural heritage of Osijek and Slavonia.