This study investigated the metadata knowledge and the use of institutional repositories by librarians in university libraries in southwest , Nigeria. Descriptive survey design of the correlational type was adopted for the study. Total enumeration method was used to select one hundred and nineteen (119) librarians in university libraries that have adopted the use of institutional repository using questionnaire as research instrument for data collection. The data collected were analyzed using descriptive statistics of mean and standard deviation. The findings of this study revealed that the level of metadata knowledge of librarians in university libraries in SouthWest , Nigeria, is high; the major types of content uploaded on the institutional repository are published papers 67(90.5%); doctoral and masters' theses 66(89.2%); books 61(82.4%); and articles 61(82.4%); the most frequently uploaded contents on the Institutional repository articles (x =3.62; std dev. =.5899); books (x =3.55; std dev. =.7610); doctoral and Master "theses (x =3.52; std dev. =.7257); and conference reports (x =3.51; std dev. =.7069); there is no significant relationship between metadata knowledge and the use of institutional repositories (r =.123; p > .298; N= 74). The study concluded that metadata knowledge does not influence the use of institutional repositories by librarians in university libraries in South West Nigeria. This is because librarians in university libraries in SouthWest Nigeria do not depend on their knowledge of metadata to make use of institutional repository. The study therefore recommended that the university library in partnership with the university management should work out a policy that will see to it that contents such as technical reports, unpublished reports, and raw data are uploaded on the institutional repository. Other universities should also implement the use of institutional repository to improve the visibility of their institution globally.