This study aimed to estimate the determinants of intra-trade of Muslim's countries - members of the Organization of the Islamic Conference - during the period (1970 -2006), using recent econometric techniques for the panel data. In introduction, the study examined the religious, historical and current economic dimensions, pressing to achieve economic cooperation and integration among member states. The study also reviewed the most important applied research, which dealt with aspects of economic cooperation of Muslim's countries and other states, with reference to the situation of foreign trade of Member States, and its evolution over time, and commodity structure, and the most important obstacles encountered. To achieve the objective of the study, available data for a sample size of 18 OIC members over the period (1970 -2006) were collected and considered for estimation purposes. The study employed panel analysis approach to estimate the determinants of intra-trade of OIC members, in the framework of static analysis using the pooled least squares models, fixed-effects and random models. As for dynamic analysis, Mean Group Estimator (MGE) and Pooled Mean Group Estimator (PMGE) were used for estimation. In estimation, the study used macro variables like gross intra-trade (intra-export and import amongst member states ) as a dependent variable and inflation rate, volatility of exchange rate, GDP, export to rest of the world and import from the world as independent variables. All mode variables were found individually integrated of order one as well as cointegrated. Estimated error correction model using (PGME) indicated that, in the short-term, intra-trade of OIC members is negatively dependent on inflation rate by (0.21), volatility of exchange rate by (0.17) and export to rest of the world by (0.013), whereas it was found positively dependent on GDP by (0.39) and import from the rest of the world by (0.66). The model also indicated that the intra-trade of OIC members adjusts towards long run equilibrium by (16.23%) in every period of time. The speed of adjustment was found to take 6 years of time to equilibrium value.