The main aim of this research is to survey the status of the use of web 2.0 tools in knowledge sharing of 37 librarians who work in central libraries of Tabriz Governmental Universities. Findings indicate that they desire to use such tools. The most important reasons for the usage of web 2.0 tools in knowledge sharing are speed and ease of use, managing personal knowledge, easier communication with users and colleagues. More than half of them stated that lack of knowledge in the use of these tools and lack of familiarity with these services are the main obstacles. The relationship between age, gender, education, level of experience, library section they belong to and (a) the rate of usage of web 2.0 tools in knowledge sharing, and (b) the level of familiarity with knowledge sharing concept is not significant. However, there is significant relationship between librarians' education and the usage of web alerting as well as between the level of familiarity with knowledge sharing concept and the level of use of some web 2.0 tools.