The Internet provides an immense source of data. It subiquity, general availability and ease of use make it potentially an ultimate tool to search for information. However,the availability of data does not directly imply the availability of information. Web search engines, sophisticated tools designed to retrieve information from the Internet, could be rather unsatisfactory when dealing with todays size, complexity and dynamic of the web. A series of advanced techniques has been proposed to leverage search services in order to increase the user satisfaction. Collaborative search is an innovative search paradigm based on implicit collaboration and knowledge exchange between inquirers. In this paper, we focus on comparison of several query similarity measures for the use in a collaborative search environment.