This study aims to investigate the direct effect of the relationship between Leader's Dark Triad Personality Traits and Workplace relationship quality for employees in medical centers and hospitals in Mansoura University.This research adopts a quantitative method as a research methodology. Hence, the data was gathered from 380 employees in Mansoura University hospitals (82.6% response rate).The study findings showed that leader's dark triad personality traits have a significant negative effect on workplace relationship quality. Theoretical and practical implications were then discussed.