This study estimates three hypotheses of OPEC behavior: market-sharing, target revenue and competitive model for the period 1980 to 2000 for all OPEC courtiers except Iraq. To examine co-integration relation for oil production, we use ADF test in OLS estimation. Also we use ARDL approach to examine these hypotheses and the long run relationship of them. Results indicate none of three hypotheses fit completely with OPEC behavior; Market sharing model is consistent with most of OPEC countries, but not for all; Saudi Arabia is consistent with market sharing and price maker. Some of estimations of Target revenue and Competitive models are spurious, but among countries, which have statistically significant estimations, none of them is consistent with competitive model. All estimations of Target revenue model with OLS to all OPEC countries are spurious except one (behavior of Iran is consistent with partial target revenue) and also the long run relationship of all estimations of Target revenue model with ARDL to all OPEC countries are meaningless except one (behavior of Qatar isn’t consistent with target revenue model).