In near future, none of factors like information technology will be able to change organizations. This study is a step toward investigating the effect of information technology and its dimensions (speed, easiness, accuracy and reliability) on organizational performance with clarifying the role of mediator variable of organizational structure on the staffs in Ilam Melli Bank. This study is a descriptive –survey one. Its statistical population is all of the staffs in Ilam Melli Bank, questionnaires are used to data collection, its validity was confirmed by experts and its reliability is 91% . For data analyzing, structural equations with utilizing LISREL software was used. Information technology has a positive and significant effect on organizational performance with clarifying the role mediator-variable of organizational structure. Information technology dimensions (speed, easiness, of accuracy and reliability) also has a positive and significant effect with regarding and clarifying the role of organizational structure mediatory. Training of staffs in information technology, modification and adjustment in the structure of jobs with installation and development of software applications will enhance the performance and will cause knowledge sharing and will facilitate organizational learning and accelerate the implementation of administrative process and reduce  the amount of work.