Toxic leadership causes serious problems and losses in organizations when it is not recognized and therefore not prevented. This type of leadership can negatively affect organizations by affecting employees or employees by affecting organizations. Understanding and making visible the effects of toxic leadership on both organizations and employees will contribute to understanding the source of the problems experienced in workplaces.  In this context, the documents on this subject in the literature were scanned and their contents were classified. In the content of the study, firstly the differences between leadership and toxic leadership are explained, then the characteristics, behaviors and reasons of toxic leaders are explained. Finally, the effects of toxic leaders on both organizations and employees are included. These effects were seen on the employee in terms of psychological, physiological and behavioral (organizational conflict, organizational commitment, employee reputation, etc.), and on the organization in terms of organizational effectiveness and efficiency (mismanagement, low production and performance, decreased job satisfaction and satisfaction, increased organizational costs), organizational climate, culture and reputation.