Some parishes will be left priestless if disaffected Anglicans continue "jumping ship" to the Vatican, the Archbishop of Canterbury has warned.
The Pope has created a special enclave in the Roman Catholic Church for Anglicans unhappy with their Church's decision to let women become bishops.
But Dr Rowan Williams told Rome's Vatican Radio the defections would pose a "practical challenge".
Earlier this month three serving and two retired bishops joined the scheme.
In the interview, Dr Williams said: "There will be at least some parishes which will now be without priests so we have a practical challenge here and there to supply."
He added that it would also be difficult to sort out "what is really going to be possible" for proposals to share uses of churches.
There have been splits among Anglicans over the issues of homosexuality and the ordination of women.
Dr Williams said that did not mean that all disaffected Anglicans thought conversion was the only solution.
He said: "There are still a great many Anglicans who call themselves traditionalist who have no intention of jumping ship at this point, who are in considerable confusion and distress at the moment.
"But they don't necessarily think that, if the Church of England isn't working for them, the only option is Rome."
The men who have already announced their defections were all suffragan or assistant bishops rather than those in charge of dioceses.
The archbishop said there was no ill-feeling but he felt "regret and respect" over their decision.
He also added that he did not see the Vatican scheme as an "aggressive act" which was "meant to be destabilise" the relation between the two Churches but one that would people people to evaluate "Anglican legacy".
Dr Williams also met Pope Benedict XVI for a private visit during his trip.