This study examined from a social exchange perspective the influence of leader-member exchange (LMX) on the trust of subordinates in their supervisors as well as their perception of support received from their medical organization supervisors and the subsequent effect of such on organizational citizenship behavior (OCB) in subordinates. Two hundred valid supervisor-subordinate (head nurses-nurses) dyads from 3 medical centers and 3 regional hospitals took part in this study, which found that the quality of leader-member exchange affects nurse trust in their supervisors as well as their perception of supervisor support, which consequently promotes OCB on the part of nurses. Findings imply that a higher level of LMX can enhance nurses' commitment, significantly reduce turnover, and promote their OCB, resulting in greater organizational effectiveness.