With the victory of the Islamic Revolution of Iran in 1978, the foreign policy of the Islamic Republic of Iran transformed and distanced itself from traditional nationalist frameworks. One of the most prominent features of Iran's foreign policy during this period was the adoption of a "nation-based" approach; an approach that was based on Islamic concepts such as the unity of the Islamic Ummah. This approach was manifested in the form of supporting Islamic movements, confronting Western powers, and confronting some regional countries.

The purpose of this research is to examine and analyze the consequences of adopting a nation-based approach in the foreign policy of the Islamic Republic of Iran during the years 1978 to 1997 on the national interests of the country.

The main question of the research is: What impact has adopting a nation-based approach in the foreign policy of the Islamic Republic of Iran during this period had on Iran's national interests?

The research method is descriptive-analytical and uses documentary data and library resources.The research findings show that the policy of nationalism at the discursive level strengthened Iran's position among some Islamic groups and consolidated the ideological identity of the Islamic Republic, but in practice it led to challenges in the field of national interests.

The research conclusion indicates that the foreign policy of the Islamic Republic, in order to realize national interests, requires establishing a balance between value principles and realistic considerations