The libraries collections, specially its rare and special books collections, are a cultural good from a historical and sociological point of view. However, the book and even more libraries are not clearly among the items to be preserved in the Brazilian Constitution and in international organizations. There is a lack of discussion and legal cover as the bibliographic collection as a heritage to be preserved. The absence of an overall view is prejudice to the preservation of library collections. Based on the legal texts dealing with the book and libraries, the paper discusses the role of libraries in the preservation of historical collections within the public institutions.