The main purpose of this study was to make a causal model of trust and organizational silence to managers' commitment to university. This study was a descriptive-correlation research and statistical population consisted of all students (n=215) selected through random sampling method at Shiraz University of Medical Sciences during an academic year in 1392-93. Research tools included trust-in-managers questionnaire by Forsite and Adams (2004), organizational silence questionnaire by Brinsfield (2009) and Queen (2000) that were distributed between the sample after calculating their validity and reliability; moreover, data was analyzed through Path Analysis method based on Baron & Keni (1986). Afterwards, results of the research showed that students' trust in managers was a significant negative predictor of some aspects of students' silence, while it considered as a significant positive predictor of commitment to university; in addition, silence variables such as acquiescent Silence and deviant Silence significantly anticipated the rate of commitment to university negatively; how much the confidence to directors is higher, therefore, students are less silent and freely express their ideas and constructive comments in a healthy environment; the more trust in the organization, then the less silence of students. Consequently, Educational administrators are responsible for promoting confidence among students that would be certainly a commitment to maintain the goals and mission of higher education.