Cardinal Seán Brady has asked for prayers for Cardinal Cahal Daly, who remains seriously ill in Belfast City Hospital.
The 92-year-old prelate was admitted to hospital on Sunday.
Cardinal Brady said ‘I am confident that many people will offer Cardinal Daly the help of their prayers in this his hour of need.’
Cardinal Daly was taken from his home in south Belfast after suffering heart problems.
He is being treated at the City Hospital's coronary care unit.
Cahal Daly became Archbishop of Armagh and Primate of All Ireland in 1990 and served in this role until his retirement in 1996.
He was created Cardinal in 1991.