Portugal's president has said the country's predominantly Roman Catholic population will vote on whether to legalise abortion on 11 February.
Portugal has among the tightest abortion laws in Europe
Anibal Cavaco Silva said he agreed to the vote because the issue still dominated public debate in Portugal.
The country will be asked if they wish to approve the right to terminate a pregnancy within the first 10 weeks.
Abortions are only legal in Portugal in cases of rape, foetal abnormality or if a woman's life is in danger.
"The fact that this is a problem that continues to foster a live debate in Portuguese society [...] is reason enough to call on citizens to express their opinion with their vote," said Mr Cavaco Silva.
The referendum has already been approved by Portugal's parliament.
Pro-choice organisations in the country say some 10,000 women each year need medical treatment after illegal abortions.
The Roman Catholic Church and right-wing Christian Democrats have said they will campaign against changing the law.
They argue that an unborn child should be protected as forcefully as it is after it is born.
In 1998, a slim majority voted in favour of relaxing the law but the result was ruled invalid because of a low turnout.