The group held a small demonstration in front of Notre-Dame Basilica in Montreal's Old Port.
As children, the Duplessis orphans were put into church-run psychiatric institutions in the 1940s and1950s after being falsely declared mentally ill.
Louis-Joseph Hébert, 75, said he endured years of sexual and physical abuse at the hands of the nuns and priests who ran the government-subsidized orphanage where he was raised.
"They never called by the names, they always called 'Hey bastard — bastard, come here.' We grew up like that," he said.
Archbishop Christian Lepine said the church itself is not responsible for the terrible acts the Duplessis orphans suffered.
"If it's someone in an institution, even if it's someone who's there in the name of his own religion —being a Christian— if he does something unjust, well, it's still as a member of the church. It's not the church itself," he said.
Hébert said though he suffers from cancer, he will be taking part in demonstrations every Good Friday in the hope of finally getting the apology he wants.