This study investigates the effect of stock liquidity and stock liquidity risk on information asymmetry in Tehran Stock Exchange (TSE) listed companies. In this study, the bid-ask spread is considered as the criterion of information asymmetry. In addition, stock trade volume and the number of stock trades are considered as the criteria of stock liquidity. Some variables such as size, stock price, beta and growth are also considered as control variables. To test the hypotheses of the survey, 202 TSE listed companies over the period 2007-2012 are considered based on the multiple regression (Panel) method. The evidence shows that both proposed criteria, stock liquidity criterion as well as the stock trade volume and the number of stock trades, had negative effects on information asymmetry, but this effect is not statistically meaningful. In addition, evidence shows that stock liquidity risk had positive effect on information asymmetry, which is statistically meaningful. Research results also show that firm size and beta had positive and meaningful effects on information asymmetry. Finally, the results show that growth and stock price had negative meaningful effects on information asymmetry.