The Italian parliament on Wednesday enacted legislation which recognises same sex civil unions.
The Bill, which had already been approved the senate in February, marks the end of three decades of struggle by gay rights groups.
It went through on a government confidence vote and in the face of strong Catholic Church and Catholic lay group opposition.
The Catholic opposition has already said it will call for an abrogative referendum while the Northern League leader Matteo Salvini has called on League mayors not to respect the new legislation.
Supporters of the Bill regularly pointed out that last summer the European Court of Human Rights in Strasbourg ruled Italy to be in violation of human rights through its failure to offer adequate legal protection to same sex couples.
Until now, Italy was the only major western European power not to have some form of same sex civil union or same sex marriage legislation on its statute book.