This study aims to identify the impact of the Iranian nuclear deal with the P5+1 on the Iranian-Saudi relations through tracing Iran's nuclear file path from its early stages until reaching the JCPOA. Iran considered this deal an international recognition of Iran's regional power and its right to have a nuclear program for peaceful purposes. This has posed a clear threat on the regional balance of power, disquieting Saudi Arabia. On one hand, despite the US assurances to KSA and the relative openness of the Iranian political discourse, there have not been any signs of improvement on the Iranian Saudi Relations. On the other hand, Trump's policies may increase Iran's hostility and therefore a state of wariness will continue to be the main feature in the Iranian Saudi relations.