He was pastor of Hàm Long Parish, in Hanoi, North Vietnam, from 1950 to 1955.

[2] He was appointed archbishop of Hanoi in 13 April 1994[3] and elevated to Cardinal in November 1994.

[4] Since nearly the very beginning of his religious life, he was under house arrest, unable to carry out his duties to the nearly 100 parishes under his jurisdiction.

He began to compile in lục bát the entire life of Jesus, the Gospels, Christian doctrine, and the commandments of God and the Church.

He was created a Cardinal-Priest of Santa Maria Regina Pacis in Ostia Mare by John Paul II during the Consistory of 26 November 1994.