A study was carried out during 2001 to 2010 to illustrate the profit of momentum strategy in Tehran stock Exchange, and possibility of higher abnormal return based on past performance trends. In this study, the effects of two substantial variables including size and liquidity on profitability of momentum strategy in Tehran stock Exchange were investigated. The study was conducted in two sub-periods: 2005-2010, and 2007-2010. The first is due to a significant change in the number of stock companies after privatization, and the second is to cover the effects of global financial crisis on Iran's economy. Our sample includes three separate samples of all stock market joined companies before the mentioned related periods that have been traded in at least half of the total trading days in the related period. Results showed that using momentum strategy in Tehran Stock Exchange created negative returns in all periods. Moreover, liquidity factor did not affect the profitability of momentum strategy. Meanwhile, considering size as another fundamental factor, the positive effect of small stocks was identified only in one period, from 2005 to 2010. In other periods, however, it led to negative returns.