It can be traced back to the 17th century that Byzantine-rite, Hungarian-speaking Christians lived in the Eastern part of the Great Hungarian Plain. In 1875 the Vicariate of Hajdúdorog was created for them, which included the 33 Hungarian-speaking parishes of the Munkács Diocese as well. Later, in 1913 Franz Joseph I, resp. Pope Saint Pius X established the Diocese of Hajdúdorog. The founding bull named the diocese after Hajdúdorog, and the first bishop of the diocese, István Miklósy made Debrecen and later Nyíregyháza the episcopal residence. As a result of the Trianon peace treaty, 75 parishes of the diocese came under Romanian rule and these were returned by the Holy See to the jurisdiction of the Greek Catholic bishops in Romania; the four parishes that got to Czechoslovakia were attached to the Mukacheve (Munkács) Diocese - later these came under the jurisdiction of the Presov (Eperjes) Diocese. From 1968 the Holy See authorized the bishopric to provide pastoral care to all of the Greek Catholics in Hungary. The only exception is the territory of the Miskolc Exarchate (Administration) but it was under the authority of the Bishop of Hajdúdorog between 1946 and 2011. (From 2011 it has an independent bishop and cathedral in Miskolc and its boundaries are contiguous with the borders of Borsod-Abaúj-Zemplén County.)
The government documents of the Diocese of Hajdúdorog from its creation in 1912 make up the majority of the archives, founded in the same year. Later the fonds of a few established Greek Catholic church organizations were placed in the archives. In 1913 the documents of the defunct Vicariate of Hajdúdorog and in 1976 the Archives of the Archdeaconry of Hajdúdorog were placed in Nyíregyháza.
Despite the two world wars the archival holdings remained intact, only two dossiers disappeared. The sorting of the archives started in 1975, when an appropriate storeroom and office was provided. The 1989/90 democratic transformation changed the future of the archives, because the personal, financial and research conditions were significantly liberalized. The overview of the previously unclassified documents took place between 1993 and 1997. The archives were completely renovated and at last the documents were placed on the shelves in boxes. The archival holdings of the Theological College were received and the computer-processing of the archival aids started as well. In the autumn of 2003 the library, which was next to the archives, moved into the new building of the Saint Athanasius Greek Catholic Theological College, therefore significant storage space became available for the archives, which allowed the delivery of the documents of historic value from the parishes.
Address: 4400 Nyíregyháza, Bethlen Gábor u. 5.
Postal address: 4401 Nyíregyháza, Pf. 60.