The Eparchy of Krizevci, also referred to as the Byzantine Catholic Church of former Yugoslavia is a Uniate Church, or Slavonic-Rite Catholic Church.
It operates principally in former Yugoslav republics of Croatia, Macedonia, and Bosnia; it gathers Serb faithful in Croatia (mostly Žumberak) and Macedonian Slavs in FYR Macedonia as well as some Ukrainians in Northern Bosnia.
The Church is of the Slavonic Rite or Eastern Rite that uses the Byzantine Liturgy. However, it is considered Catholic in the sense that it is in full communion with the Roman Catholic Church, accepts the authority of the Pope in doctrinal matters, such as the existence of purgatory and the use of unleavened bread. It does not follow the common Latin (Western) Rite of the Roman Catholic Church.
The Church began in the 17th century with the Marča Union of 1611 (in the Orthodox monastery called Marča, near Ivanićgrad) which had as a goal the Uniatization and eventual Catholicization of the Serbs living in the Habsburg Empire, today's Croatia. The Union was resisted by most of the fiercely Orthodox Serbs (particularly by the metropolitan of Karlovci, Arsenije III Čarnojević). However, it did take hold in a particular regiment of Serbs of the Žumberak regiment of the Krajina.
Despite fierce tensions, the Serbs in were given their own eparchical bishop by Pope Pius VI on June 17, 1777, with his see at Križevci, a town northeast of Zagreb. Initially, he was made suffragan to the Primate of Hungary, later (1853) to the Latin Archbishop of Zagreb.
The eparchy expanded to embrace all Uniates in Yugoslavia when the country was founded after World War I. The eparchy gathered a heterogeneous collection of five groups: ethnic Serbs from Žumberak, Croatia, Ruthenes in Slavonia and Serbia who had emigrated from Carpatho-Ukraine and Slovakia around 1750, Ukrainians who emigrated from Galicia (now the Ukraine) around 1900, Slavic Macedonians converts from missionary activity in the 19th century as well as a few Romanians in the Serbian part of the Banat (Vojvodina).
In September of 2003, the Uniate faithful of Serbia and Montenegro (numbering about 22,000, exclusively Ruthenes and Ukrainians) were given their own jurisdiction under a bishop that is to be appointed in the see of Ruski Krstur in Serbia.