Pope Francis has said he may consider ordaining married men - under very specific circumstances - to address the shortage of Catholic priests.
He was speaking about the possibility of viri probati (men of proven faith) carrying out some duties.
"We have to give a thought to whether viri probati are a possibility," he told German newspaper Der Zeit, his words translated by Reuters.
Such men, he said, could possibly work in isolated areas.
The Latin phrase viri probati is used to refer to married men of strong faith, who are often older with grown children.
Despite his remarks on the limited possibility of allowing married men to enter the Church, the Pope ruled out dropping celibacy as a requirement for the priesthood.
He said that voluntary celibacy - giving young priests an option - was "not a solution" to the question.
Analysis: David Willey, BBC Vatican correspondent, Rome
One of the most serious problems facing the Catholic Church is the growing shortage of priests. A quarter of Catholic parishes worldwide now have no resident priest.
Differential growth patterns mean that parishes set up in Europe hundreds of years ago are no longer aligned with the developing world's expanding Catholic population.
Although the total number of priests worldwide remains more or less steady at just over 400,000 new vocations are insufficient to replace an ever more ageing priesthood.
Campaigners for reform of ordination have, in the past, suggested that married men could supplement the clergy in carrying out priestly duties.
Roman Catholic priests are required to abide by the rule of celibacy upon ordination with very rare exceptions - such as married Anglican ministers who convert.
It is seen as a symbol of the devotion of one's life to God, though the rule does not apply to Eastern Rite Churches.
The Vatican also confirmed the Pope would visit Colombia in September.
Peace talks between Farc leftist rebels and the Colombian government, in which the Vatican played a role, were successfully completed last year.
The Pope will spend several days in Colombia, without visiting any other neighbouring countries - something a Vatican envoy said "shows the importance Francis attributes to this trip, and ultimately Colombia".