The establishment of the Islamic Republic in Iran led to the creation of a unique alliance with Lebanon's Hezbollah based on its strategic interests and religious and strategic considerations. Accordingly, the main question of this study may be given as: what may be regarded as the effects caused by IRI`s strategic alliance with Lebanon's Hezbollah on IRI`s strategic interests? The main claim of the research is that the unity of the Islamic Republic with Hezbollah has led to the provision of strategic interests of Iran in the political, military and security dimensions. Studying the problem with regard to the theories of coalition as viewed in offensive and defensive neorealism, one finds the alliance as being offensive and defensive natures both. Some strategic benefits of the alliance may be counted as: preparing thr grounds for power and security, increasing strategic depth and deterrence of the Islamic Republic of Iran, Confronting Israeli-American hegemony in the Middle East, decreasing Israeli national security rate, maintaining the axis of resistance, and expanding the alliance's network.