The Archbishop of Canterbury, Rowan Williams, is due in Rome on a visit which will include his first official meeting with Pope Benedict XVI.
The trip marks 40 years since a historic Anglican-Catholic meeting
The leader of the worldwide Anglican Church will hold private meetings at the Vatican and give two lectures.
The trip marks 40 years since a visit to the Holy See by former Archbishop of Canterbury Michael Ramsey.
But our correspondent says the Catholic and Anglican churches remain deeply divided on a number of issues.
Dr Williams will be accompanied by the head of the Roman Catholic Church in England, Cardinal Cormack Murphy O'Connor, on his six-day visit.
The archbishop's office has said nothing will be "out of bounds" in the discussions between Dr Williams and the Pope.
Pope Benedict will see the archbishop only once
The Catholic and Anglican churches have maintained a theological dialogue since resuming relations 40 years ago.
But the BBC's David Willey in Rome says there are differing views on several issues, particularly the plans for the consecration of women as bishops by the Church of England.
The visit is not expected to make any significant progress in re-establishing full communion between the two churches, the goal set 40 years ago, our correspondent says.