To what extent has been continuity and change in the revolutionary Iran foreign policy since 1979? This question is examining the Iranian foreign policy over the last twenty-seven-year by using two major theories in the fields of International relations and comparative foreign policy explanations. While the systemic theory, represented by neorealism theory in this research, argues that international system drives states foreign policies, domestic and statist explanations argue that domestic political factors play major role in driving and shaping states foreign behaviors. My research will use these different approaches to study the Islamic Republic foreign policy under different leaderships – Khomeini, Rafsanjani, Khatami, and Ahmadinejad – since its establishment in February 1979. Since this research is using different international variables – the Iran-Iraq War (1980 – 1988), oil prices, and the existences of the United States armed forces in the Middle East, as well as different domestic and Statist political variables – leaders’ orientations, decision structure, domestic political oppositions, and interest groups.