The study investigates the materials of the Russian ambassade S. Islen’ev and M. Griazev to the court of the Qizilbash shah Safī, stored in the funds of Russian State Archive of Ancient Acts. The archival file is a set of documents reflecting the process of the exchange of embassies between the Russian Tsardom and the Safavid Empire in 1635–1637. The aim of the embassy of S. I. Islen’ev and M. K. Griazev was to discuss some topical issues of bilateral relations such as duties, restitution cases, the purchase of Iranian niter etc. In addition, the documents describe the features of the court ceremonial in relation to foreign guests. The good preservation of the documents gives researchers the opportunity to study the ambassade at great length. As for the results of the embassy of Islen’ev and Griazev, they can be regarded as moderately positive. The high level of bilateral relations and their positive nature (“friendship and love”) were confirmed. In addition, the Safavid side once again confirmed the need to verify the membership of embassies and trade missions. On the other hand, the attempt of the tsar’s ambassadors to purchase niter in the shah’s possessions ended in failure. In general, the embassy of S. Islen’ev and M. Griazev was an ordinary diplomatic mission in terms of tasks and results, but this is its value for a scholar. Sustainability of the bilateral agenda and the presence of well-known “stumbling blocks” in its framework contributed to the regularity of Russian-Safavid ties.