Purpose – The purpose of this paper is to examine the mediating role of leader-member exchange in the relationship between organizational justice and job performance. The study primarily focused on the perception of university libraries personnel regarding organizational justice practices and the quality of their relationship with their supervisors and how such perceptions predict their job performance. Design/methodology/approach – This study tested a sample of 15 university libraries of Islamabad, Pakistan. Data were accumulated through questionnaire and analyzed on SPSS. Descriptive and correlation analysis showed the positive and significant relationship between all variables. Series of separate hierarchical regression analysis were used to test the hypothesis. Findings – The result revealed that all three kinds of organizational justices (distributive justice, procedural justice and interactional justice) predict the job performance but interactional justice along with leader-member exchange impacts more strongly on job performance. Research limitations/implications – The result of this study will assist the library leadership to foster a greater sense of employee worth and teamwork among staff members by implementing organizational justice practices. The study would also enhance the interest of Pakistani Library Information Science professionals and researchers toward behavioral aspects of library administration. Limitation: The results of this study may not be generalized to all universities and other industries of Pakistan as data is collected only from 15 universities of Pakistan. Second, interpretations of results are limited by the cross-sectional design of study and does not allow casual conclusion. Originality/value – According to researcher knowledge very few studies have been conducted on the management side of libraries in Pakistan. This paper is the first study in Pakistan Librarianship that examines the linkage between organizational justice, leader-member exchange and job performance.