The Assyrian Church of the East faced a split in 1898, when a bishop and a number of followers from the Urmia area in Iran entered communion with the Russian Orthodox Church, and again in 1964 when some traditionalists responded to ecclesiastical reforms brought on by Patriarch Mar Eshai Shimun XXIII (1908??975) by forming the independent Ancient Church of the East.

Today the Assyrian Church has about 170,000 members, mostly living in Iran, Iraq, and Syria. The Patriarchate of the Assyrian Church of the East is in exile in Chicago, and that of the Ancient Church of the East is in Baghdad.