The proposed paper aims to examine the role of religion in Iran’s foreign policy. Being the world’s sole Islamic Republic, Iran’s domestic and foreign policy has often been considered to be completely driven by religious ideology. However, at a closer look, realpolitik appears to be the guiding principle of Iran’s foreign policy. While in the case of Lebanon Iran has nurtured a client relationship with the Shiite Hezbollah political movement, this was dictated by Iran’s strategic interests and not by its religious affiliation. When Iranian interests ordered otherwise, then religion would be sidelined. This was the case in the Nagorno Karabagh war of the early 1990s, when Iran indirectly supported Christian Armenia in its war against Shiite Muslim Azerbaijan. Similarly, Iran did not object the US invasion of Afghanistan, which aimed to topple another Islamist regime, the Taliban. Although Iranian foreign policy is based on realpolitik, the Iranian regime has increasingly employed religious rhetoric in its foreign policy. In this paper it is argued that religion per se does not play a key direct role in the formation of foreign policy preferences in Iran. Nonetheless, the use of religious rhetoric in foreign policy does play a major symbolic role in the domestic field as a tool for the legitimisation of the regime. This may be due to two main reasons. The rise of the regional and global role of religion and the recognition that religion as a key identity element in the Middle East cannot be dismissed.