Ruthenian Greek Catholic Church

The Ruthenian Greek Catholic Church, also known in the United States as the Byzantine Catholic Church, is a sui iuris (autonomous) Eastern Catholic particular church based in Eastern Europe and North America that is part of the worldwide Catholic Church and is in full communion with the Holy See. It uses the Byzantine Rite for its liturgies, laws, and cultural identity. The Church originated at the Union of Uzhhorod in 1646, when Orthodox East Slavs with a Rusyn identity in the Carpathian Mountains entered into communion with the Pope.

The Church does not have a unified structure. Its numerically largest jurisdiction is in Europe, the Greek Catholic Eparchy of Mukachevo, which reemerged in Ukraine after having been suppressed by the Soviet Union. There is also the Apostolic Exarchate of the Greek Catholic Church in the Czech Republic, founded in 1996. Both of them are exempt territories immediately subject to the Holy See.

The Metropolis of Pittsburgh is the Church's self-governing jurisdiction in the United States, created in the early 20th century for Rusyn immigrants. Today it includes many members of non-Eastern European descent while still continuing Ruthenian traditions. In 1956 the U.S. jurisdiction stopped using Ruthenian Greek Catholic to describe itself, and since 1969 it has called itself the Byzantine Catholic Church, also being reorganized as a metropolitan church by Pope Paul VI. This makes the Byzantine Catholic Church the only self-governing Eastern Catholic metropolitan church in the United States. In 2022 the Slovak Greek Catholic eparchy for Canada was changed to an exarchate and was subordinated to the Byzantine Catholic Metropolis of Pittsburgh.