A multidatabase system (MDBS) is a confederation of preexisting distributed, heterogeneous, and autonomous database systems. There has been a recent proliferation of research suggesting the application of object-oriented techniques to facilitate the complex task of designing and implementing MDBSs. Although this approach seems promising, the lack of a general framework impedes any further development. The goal of this paper is to provide a concrete analysis and categorization of the various ways in which object orientation has affected the task of designing and implementing MDBSs. We identify three dimensions in which the object-oriented paradigm has influenced this task: the general system architecture, the schema architecture, and the heterogeneous transaction management. Then we provide a classification and a comprehensive analysis of the issues related to each of the above dimensions. To demonstrate the applicability of this analysis, we conclude with a comparative review of existing multidatabase systems.