Purpose This study aims to evaluate the effect of workplace ostracism on organization-based self-esteem (OBSE), organizational silence and knowledge sharing. Design/methodology/approach The statistical population of this research includes the employees of University of Isfahan in Iran. The structural equation modeling method is used to analyze the data and the conceptual model using 130 participants. Findings The empirical results suggest that ostracism and organizational silence influence knowledge sharing, negatively. Ostracism influences organizational silence, positively; and ostracism influences OBSE, negatively. Furthermore, organization-based self-esteem influences knowledge sharing, positively. In addition, the indirect relationship from ostracism to knowledge sharing through organizational silence was confirmed; however, the mediating role of OBSE in the relationship between workplace ostracism and knowledge sharing was not confirmed. Originality/value This research is among the first to evaluate the relationship between workplace ostracism, knowledge sharing, organizational silence and OBSE simultaneously.