Like other scholarly journals, OA journals have a peer-reviewing process that complies with the usual reviewing rules and ensures the scientific quality of their articles:

·       Examples of peer-reviewed Open Access journals

Furthermore, the journals themselves are assessed using the same bibliometric indicators as for other journals:

·       There are almost 500 open access journals in the database of Thomson Reuteurs ISI, Web of Science

·       PLOS ONE has been accepted for coverage in the Science Citation Index, Web of Science and the Journal Citation Reports.

·       All journals published in Biomed Central receive an "Impact Factor". They have good scores compared to those of traditional journals in their area. 

These examples confirm that researchers deem OA journals and their content worthy of interest from a scientific point of view. ISI’s impact factor is meant to reflect the citation frequency of an "average article" published in a journal during a given period of time such as a calendar year.

Some of these journals are now considered authorities:

o   PLOS Medicine: 12.185 (Impact Factor in 2008) - PLOS ONE = 131 (factor: H5) in 2013

o  BMC Biology: 4.734 (Impact factor in 2008) - BMC Biology’s factor was H5 in 2013

Since OA journals are more visible, they have a larger readership and their articles are cited more often, which increases the journal’s impact. A series of recent studies has demonstrated the advantages of Open Access.

Source : Stevan Harnad, Making AgriScience Open Access