Abstract: This research aims to investigate influential factors which affect knowledge sharing in virtual organizations. The case study used for the purpose of this research is one of the largest telecommunication organizations of Iran. The data gathered in a 2 month period, between June 2017 to August 2017. The studied sample includes 170 staff chosen from Irancell’s personnel. In order to analyze our findings, we have employed Factor analysis, Cronbach’s alpha, Kolmogorov-Smirnov one-tailed t-test and Friedman Data analysis on collected data. Our analysis has shown that structural, technological, human and cultural factors play the most significant roles on knowledge sharing in virtual organizations. Also, priority analysis has highlighted that structural factors account for the most prominent variable. The findings show that all four proposed hypotheses have been confirmed. Between four factors which have been analyzed, the structure was rated in the first place. The results also indicate that organizational culture, technology and human factors are ranked in second to fourth positions respectively. It can be inferred that managers and authorities need to implement knowledge sharing practices in virtual organisations all four identified factors should be taken into consideration. This study is one of the first studies which specifically uncover the knowledge sharing practices in virtual organisations in Iran. This is very crucial for virtual organisations to develop and improve their knowledge sharing practices.