This study is an inquiry into the history of political relations between the Soviet Union and Iran. The focus of the work is the Gorbachev period from 1985 up to 1991. Although geostrategic considerations, national security concerns and economic interests continued to be the fundamental determinants of Soviet-Iranian relations during these years, they assumed new dimensions resulting mainly from regime changes, alterations in ideological trends as well as political and military developments on both sides. The study evaluates the nature and implications of these changes in the light, in particular, of 'new thinking' in Soviet Third World policy. After 1985, growing evidence indicated that Soviet policy in the Third World was undergoing changes consistent with the basic principles of 'new thinking' in the theory and conduct of Soviet international relations. A revitalization of the Soviet role in the world and a move from standard policies practised in the past, just as it changed the nature of East-West relations, affected Soviet Third World policy too. During the period with which we are concerned the Islamic revolutionary regime in Iran, still very much a political riddle to the outside world, was approaching a turningpoint in its political orientation, one that was obscure at the time as a result of the fact that the expression of foreign policy developments in Iran after the Islamic revolution had been treated with secrecy and regarded as the exclusive right of the clergy. The study examines Iran's national, historical and geographical motives in this context, considering its philosophy and political culture together with the basic mechanisms of its policy-making process especially in the most recent years. The study also addresses a number of crucial questions: Whether the shift in Soviet policy towards Iran after 1985 was substantive or merely involved tactical changes to increase the efficacy of old policies long in place? How did the former Soviet Union try to translate its power into political influence over Iran? How did Soviet foreign policy behaviour in the region change as a result of 'new thinking'? And how did the Soviet Union perform in relation to national security with reference to the Islamic issue and regional crises on its southern frontiers? The opening chapter of the work covers the entire historical background of relations between the Soviet Union and Iran, and the pre-Soviet monarchical relations of Tsarist Russia and Persia. Chapter two contains a review of the evolution of policy in the light of the Islamic Revolution and the developments which occurred during the post-Brezhnev period. The analysis of Soviet-Iranian relations under Gorbachev in a broader context of Third World issues is the core of chapter three. An investigation of the roots of regional crises with regard to Soviet-Iranian relations and the impact of 'new thinking' in the design and conduct of Soviet foreign policy is the backbone of chapter four. Chapters five and six investigate more general policy considerations and in Soviet policy towards Iran with particular regard to regional developments. Chapter seven deals with the final phase of the Soviet-Iranian relations. The concluding eighth chapter not only pays attention to the relationship between Iran and the CIS but also the relationship with the individual republics of the former Soviet Union with whom Iran has either a common border or strong cultural ties. Here and in other chapters the study draws upon the contemporary Soviet and Iranian press as well as documentary and statistical sources, memoirs and the relevant secondary literature in several languages.