Capital asset pricing model (CAPM) considers systematic risk as the only risk priced by the market. In addition to systematic risk, Fama and French three-factor model indicates that the risk of firm size and book to market equity are also priced by the market. In addition to three risk factors addressed by Fama and French, liquidity risk and its pricing by investors in Tehran Stock Exchange is studied by a multivariable regression between 2004 through 2008. Research findings indicate that stock return in Tehran Stock Exchange can be clarified by four factors including market excess return, firm size, BE/ME ratio and stock transaction turnover in a relative plausible level (%40 in average). In the meantime, a significant relationship is observed between market excess share, firm share and stock return. No significant relationship is seen between BE/ME ratio and stock transaction turnover and stock return. In other word, only market risk and firm size (ME) are priced by market.