The 360 degrees performance appraisal system, which is considered as the most popular evaluation system today, is based on the idea that the evaluations obtained from different sources are more objective and comprehensive. Since the system gives the employee a chance to evaluate him/herself and others, it is commonly preferred. It is investigated whether rater has a similar effect on the leniency of ratings from four sources (self, supervisor, peer, and subordinate) in multi-source assessment process. In this study, the establishment and implementation of a 360-degree performance appraisal system for all task positions including both white and blue-collar personnel in a medium-sized furniture business is discussed. A total of 200 employees (39 white collar employees, 17 foremen and 144 workers) from all functional areas and reputational roles participated in the study. The findings indicate that the influence of bias on ratings was significantly greater in self, subordinate and peer feedback than in supervisor feedback.