Mosquitoes are responsible for the transmission of a large number of human diseases world-wide. Hence for preventing the spread of these diseases, it is essential to avoid being bitten by mosquitoes. Using repellents is one of very common and effective methods to reduce bites. The purposes of this article are to review the assays of repellent activity currently used and to summarize the repellent activities of the plant essential oils and their constituents against mosquitoes.