The Kurdish question has played a complicated role in relations between Iran and Turkey. After the emergence of modern states, Iran and Turkey were mostly preoccupied with security issues, which dominated relations between the two countries. Then, the Kurdish issue occupied a leading place in Iranian-Turkish relations either as a source of conflict, competition or as a source of cooperation. This article aims to review the Kurdish question in Iran, and influence of the Kurdish issue on Iran-Turkey relations since the Islamic revolution' of 1979. In this regard, it addresses the Kurdish question as a security issue in Iran and analyzes the Islamic Republic's policies with regards to it. And then it turns to Iranian-Turkish relations and analyzes the role of the Kurdish question as a source of conflict, competition and cooperation between the two countries. Finally it deals with implications of the new regional dynamics of the Kurdish question and their effects on Iran's relations with Turkey.