This study aimed to determine Organizational Citizenship behavior (OCB) role to mediate effect of transformational leadership and job satisfaction on employee performance. This Study is conducted at Bank Syariah Mandiri in Malang. Populations are 155 full time employees of Bank Syariah Mandiri in Malang. The research samples are 61 employees, selected by proportional random sampling. Data are collected directly from respondents with questionnaire. It is an explanatory research. Data analysis technique used is Generalized Structured Component Analysis (GSCA).Results prove transformational leadership does not affect on OCB, OCB affects directly on employee performance, transformational leadership affects directly on employee performance, job satisfaction affects directly on employee performance, OCB does not mediate the effect of transformational leadership on employee performance, OCB mediates effect of job satisfaction on employee performance. Based on these results, it can be interpreted that transformational leadership, job satisfaction and OCB is valuable component of an organization. This component can become a core competency to improve organizational performance. It is a source of organizational competitive advantage to face rapid business environment change.