If you consider different activities of managers, it can be seen clearly that decision making is the essence of all management activities. Decision making is counted as integral components of management and is manifested somehow in any management duty. On the other hand, organizational culture is a pattern from fundamental default that a special group created it in the solution of problems to comply themselves with the environment and achieving harmony and solidarity. This pattern is valued in the path of movement of this group and proved that is useful and efficient. As a result, it is transferred as a true way of perceiving, thinking, emotion and behavior and managers also are not separated from this fact. Therefore, the aim of this study is to investigate the relationship between organizational culture and managers' decision making style. This study is applied and terms of gathering information are survey type. The research approach is also descriptive-analytical. Statistical population is the personnel of administrative and financial assistance of units and educational centers of the 8th region of Islamic Azad University. Sampling approach is based on Cochran method and is as cluster-random. Also, we used SPSS 16 in analytical section. Based on findings of this research, following the classic management style in decision making and inattention to the role of organizational culture and participant indexes of human resource in decisions and its current affairs and, on the other hand, the lack of attention to the impact of environmental changes on the organization, in addition to the lack of dynamism and required agility in performing duties, cannot benefit from enough productivity of existing sources especially in participation section and the empowerment of human resources.