OpenDOAR -the Directory of Open Access Respositories- is a "project to list and categorise academic open access research repositories. The aim is to provide a comprehensive and authoritative list of such repositories for end-users who wish to find particular archives or who wish to break down repositories by locale, content or other measures."

There is no single list of open access repositories, OpenDOAR seeks to be a descriptive list of open access respositories, listing and describing their collecitons. However, it is important to remember that OpenDOAR is not search engine to find individual articles held within the repositories. Users are to use OpenDOAR to find the respositories for their particular needs and search within that repository.

OpenDOAR allows the user to search for a specific collection by name or browse by alphabetic listing or subject listing. Currently there are 117 collections listed in OpenDOAR under the Health Sciences subject.

OpenDOAR is a joing collaboration between the University of Nottingham in the UK and Lund University in Sweden. Both institutions are active in open access. Nottingham leads SHERPA which helped establish archives in 20 leading UK research universities and Lund operates the Directory of Open Access Journals (DAOJ)