The present study was conducted with the aim of investigating the relationship between leadership styles and employees' behavioral outcomes with respect to the mediating role of organizational politics. The research methodology was applied and descriptive-correlational in terms of purpose and conduction respectively. Statistical population included all the employees of Social Security Organization of Lorestan Province of Iran in year 2013; and 183 employees were selected as the sample size by using stratified random sampling method. In order to collect data, 5 standard questionnaires were used including transformational leadership of Bass and Avolio, William's transactional leadership, Balfour & Wechsler's organizational commitment, Chun's organizational citizenship behaviour and Karatepe's organizational politics. In order to analyze the data, the path analysis and t-test through smartPLS software were used. The results revealed that there is a positive and significant causal relationship between transformational leadership style and employees’ behavioral outcomes (organizational commitment and citizenship behavior). However, no relationship was observed between transactional leadership style and employees’ behavioral outcomes. Besides, employees’ perception of organizational politics mediates the relationship between transactional leadership style and organizational commitment.