A group of about 50,000 Byzantine Uniats scattered in southern Italy and its islands, with about 20,000 immigrants in the United States.
They comprise the, original Greek-speaking inhabitants of southern Italy, which was withdrawn from the jurisdiction of Rome and given to the Patriarch of Constantinople by Emperor Leo the Isaurian in 726.
The Byzantine Rite was made obligatory in 968, but the Norman Conquest (11th century) and the attempt to restore the Latin Rite, which began in the 11th century and continued for six centuries, prevented these people from being drawn into the GreeK Schism; they always remained faithful to the pope.
In 1467, 1566, and 1740 the immigration of the Albanians into lower Italy encouraged those who still clung to the Byzantine Rite.
The Italo-Greeks have a famous monastery near Rome (Grottaferrata), and colonies in France, Malta, and Africa.
They have churches in New York City and elsewhere in the United States.
New Catholic Dictionary