The Russian Orthodox Church (ROC; Russian: Русская православная церковь, romanized: Russkaya pravoslavnaya tserkov', abbreviated as РПЦ), alternatively legally known as the Moscow Patriarchate (Russian: Московский патриархат, romanized: Moskovskiy patriarkhat), is an autocephalous Eastern Orthodox Christian church. It has 194 dioceses inside Russia. The primate of the ROC is the Patriarch of Moscow and all Rus'.

The Christianization of Kievan Rus' commenced in 988 with the baptism of the Rus' Grand Prince of Kiev—Vladimir the Great—and his people by the clergy of the Ecumenical Patriarch of Constantinople. The ecclesiastical title of Metropolitan of Kiev and all Rus' remained in the jurisdiction of the Ecumenical Patriarchate until 1686.

The ROC currently claims exclusive jurisdiction over the Eastern Orthodox Christians, irrespective of their ethnic background, who reside in the former member republics of the Soviet Union, excluding Georgia. The ROC also created the autonomous Church of Japan and Chinese Orthodox Church. The ROC eparchies in Belarus and Latvia, since the fall of the Soviet Union in the 1990s, enjoy various degrees of self-government, albeit short of the status of formal ecclesiastical autonomy.

The ROC should also not be confused with the Russian Orthodox Church Outside of Russia (or ROCOR, also known as the Russian Orthodox Church Abroad), headquartered in the United States. The ROCOR was instituted in the 1920s by Russian communities outside the Soviet Union, which had refused to recognise the authority of the Moscow Patriarchate that was de facto headed by Metropolitan Sergius Stragorodsky. The two churches reconciled on 17 May 2007; the ROCOR is now a self-governing part of the Russian Orthodox Church.