This paper presents an empirical investigation to study the effects of macro-economic factors on the performance of stocks listed on Tehran Stock Exchange (TSE). The proposed study considers the effects of money supply, inflation rate, oil price, unforeseen changes in the course structure of interest rates as well as unanticipated changes in industrial production on stock price. Using seasonal information of stock price over the period 1997-2007 as well as regression analysis, the study has determined that risk premium of unforeseen changes in the course structure of interest rates, money supply, inflation rate and unanticipated changes in industrial production are meaningful when the level of significance is five percent. In other words, Arbitrage pricing theory model describing the expected return per share is reasonable and macro-level variables explain systematic risk on TSE.