Although its members are primarily Romanian, the Uniate Church has received even more severe treatment. By the late seventeenth and early eighteenth centuries, the Uniates, or Eastern or Byzantine Rite Catholics, had broken away from the Orthodox Church and accepted papal authority while retaining the Orthodox ritual, canon, and calendar, and conducting the worship service in Romanian. In 1948, in an obvious attempt to use religion to foster political unity, the country's 1.7 million Uniates were forcibly reattached to the Romanian Orthodox Church. Some 14,000 recalcitrant priests and 5,000 adherents were arrested, at least 200 believers were murdered during incarceration, and many others died from disease and hunger. The suppression of the Uniate Church required collaboration between the regime and the Romanian Orthodox Church hierarchy, which maintained that the Uniates had been forcibly subjugated to Rome and were simply being reintegrated into the church where they properly belonged.

That the Uniate Church survived, albeit precariously and underground, long after it officially had ceased to exist was an embarrassment to the regime and the Orthodox leadership. Even in the mid-1980s, there were still some 1.5 million believers, and about twenty "Orthodox" parishes that were universally regarded as Uniate. Besides 300 priests who were not converted, another 450 priests were secretly trained. The church had three underground bishops. After 1977 some Uniate clergymen led a movement demanding the reinstatement of their church and full restoration of rights in accordance with constitutional provisions for freedom of worship. In 1982 the Vatican publicly expressed concern for the fate of the Uniates and supported their demands. The Romanian authorities protested this act as interference in the internal affairs of the Romanian Orthodox Church.

Data as of July 1989