The research aimed to study the financial markets liquidity and returns of common stocks , Take the research  the theoretical concepts  associated with each of the liquidity of financial markets and returns of common stocks , As well as the use of mathematical methods in the practical side to measure market liquidity and Stocks  Return, the community of research in listed companies in Iraqi stock exchange that have been trading on its stock and number 85 joint-stock company, The research was based to one premise, there is a statistically significant effect for the liquidity of the Iraqi stock exchange on returns  of common stocks  to traded companies in which , Using the SPSS program was to test the hypothesis research population represented Iraq Stock Exchange for a period of three years (2010-2012) on a monthly basis. The research found the set of conclusions most important rising market liquidity for Iraq Stock Exchange  and followed increase in return of common stocks for a period of research, as the results of statistical analysis indicated the presence of a statistically significant effect of moral Iraq Stock Exchange liquidity on returns  of common stocks, and most important recommendations should the Iraq Stock Exchange work to expand its activities in electronic trading, by providing the possibility of trading for investors through the Internet, and not limited to trading within the market, and should work to reduce the transaction costs to raise the liquidity common stock, and thus reflect positively on the liquidity of the Iraq Stock Exchange brokerage firms associated with it .