Abstract: Leader-Member Exchange (LMX) and Organizational Justice (OJ) are two organizational phenomena that have gained much interest over the past decades. LMX refers to the relationship between a leader and his/her followers while OJ refers to fairness at the workplace. OJ was subdivided into three dimensions: Distributive, Procedural, and Interactional Justice. Distributive Justice (DJ) describes the fairness of physical/non physical rewards distribution, Procedural Justice (PJ) refers to the fairness of procedures implementation, and Interactional Justice (IJ) to the fairness of interpersonal treatment. Many researchers proposed that the quality of leaders and subordinates' exchanges are likely to promote followers' perceptions of fairness and that differentiation in leader-follower exchanges among subordinates may evoke feelings of unfairness and resentment. Nevertheless, the arguments on which dimensions of OJ should be related to LMX were not settled. Furthermore, some researchers suggested that differentiation among employees in the quality of their exchanges with their leaders was unlikely to affect justice perceptions. Additionally, it has been noticed that most of the existing LMX and OJ research was focusing on individuals' perceptions of these phenomena. Only a few studies examined LMX and OJ as group-level phenomena. At the group-level, OJ was called Organizational Justice Climate (OJ Climate) and it was subdivided into three climates: DJ Climate, PJ Climate, and IJ Climate. OJ Climates describe the average of workgroup members' perceptions of OJ with cach of its subdivisions referring to the corresponding workgroup average perceptions of DJ, PJ, and IJ. On the other hand, at the group-level, LMX was described using two measures: LMX Level and LMX Differentiation. LMX Level refers to a workgroup average scores of LMX while LMX Differentiation describes variance in workgroup scores of LMX. This research aimed to achieve several objectives. First, the relationships between individuals' and workgroups' perceptions of LMX and dimensions of OJ were to be investigated. Second, the relationships between LMX Differentiation and the three OJ Climates were to be examined. Third, the research was focusing on investigating the impact of workgroup size and heterogeneity on how differentiation may relate to DJ, PJ, and IJ Climates perceptions. To achieve the objectives of the study, a survey was developed and used. A purposive non- probability sampling method was followed to collect data from 173 employees working in different workgroups belonging to five economic sectors in Bahrain. The individual-level data on LMX and DJ, PJ, and IJ, which were collected via the survey, were used to examine the relationship between individuals' perceptions of LMX and dimensions of OJ. Later, the individual-level data on LMX and OJ dimensions were aggregated to the group-level of analysis in order to reflect workgroups' perceptions. The aggregated data were used to study the relationship between workgroups' perceptions of LMX and OJ Climates. Spearman's rank order correlation was used to verify the relationships between LMX and OJ dimensions at the individual-level of analysis and between LMX Level, LMX Differentiation, and all OJ Climates at the group-level of analysis. Furthermore, Partial Spearman's rank order correlation was used to examine the potential role of workgroup size and heterogeneity on the relationship between LMX differentiation and all OJ Climates. Key findings of the research indicated that individuals' and workgroups' perceptions of OJ were positively related to their perceptions of the level of exchange exerted by a leader toward his/her subordinates. Furthermore, support for the relationships between LMX Differentiation and OJ Climates was not verified. Additionally, no impact of workgroup size and diversity on the relationships between OJ Climates and LMX Differentiation was found. To be more precise, no significant relations were reported between workgroup size and heterogeneity, OJ Climates, and LMX Differentiation, except for the association between IJ Climate and workgroup size. Based on the research findings, leaders in Bahraini organizations are advised to develop high quality exchanges with their subordinates in order to increase their subordinates' perceptions of OJ dimensions which probably lead to organizational prosperity, create a healthy work environment, enhance task performance, and promote employees' welfare and peace of mind. Additionally, those leaders should be cautious of the potential negative relation of LMX Differentiation to their subordinates' OJ perceptions. Although the current study did not support this claim, care is still warranted.