In the last years, most higher education institutions have deployed open institutional repositories with the aim of disseminating their academic and scientific production. Usually, these repositories contain scientific publications and, up to some extent, learning materials and other content related to institutional activities and self-promotion. On the other hand, the Open Educational Resources movement has been promoting the creation of many open repositories with learning materials (e.g. OpenCourseWare repositories) around the world since its conception. Nevertheless, it is not clear that all this institutional effort has been adopted and fully exploited by learners. Institutional repositories are designed, build and maintained by librarians with the help of the information systems department, but their potential end-users (teachers and, especially, learners) are not part of this process. As part of a research project about analyzing social learning scenarios, we conducted 15 semi-structured interviews with the aim of better understanding the reality around the institutional repository. These interviews included questions about how learners and teachers organize their learning/teaching resources, their current knowledge and usage of the institutional repository and their needs and expectations in order to become (the repository) a useful tool for learning and teaching, respectively. These interviews were used to design a survey about institutional repository usage for all the UOC community. In this paper, we describe in detail the results of this quantitative analysis, trying to determine the reasons behind the low institutional repository usage, the main barriers that prevent teachers from using it and, at last, what can be done to improve this situation.