Currently, international competitiveness of products is a very important issue. In this regard, we have measured and studied Iran’s competitive advantage in this paper, for petrochemical product groups during time 2002-2006, with respect to importance and position of petrochemical industry in Iran’s production and export. For this reason, present paper has used the indices of Revealed Comparative Advantage (RCA) as traditional index, Constant Market Share (CMS) and Trade Map (TM) both as new indices in order to measure and study the comparative and competitive advantages in the industry. Based on the results from this study, although there is comparative advantage in major petrochemical export products, growth rate of RCA index is fluctuating for the main part of petrochemical product groups. Furthermore, Results obtained based on CMS index, indicate negative competitive performance for Iran’s major petrochemical products in target markets. Finally, based on TM index, none of petrochemical product groups have reached or sustained competitive position during the whole time under study. Thus, results indicate no specific and stable trend in competitive advantages for petrochemical product groups. Considering determinant factors of competitive advantage such as technology, quality and innovation, it is advised to give more attention to innovation, R&D activities, efficient import of technology and foreign direct investment.