The Dail in the Irish Republic has passed a bill recognising civil partnerships between same-sex couples.
The Civil Partnership and Cohabitation Bill passed without a vote. The legislation will now go to be ratified by the Seanad, the upper chamber.
The bill was opposed by Catholic bishops and a protest was held outside.
Justice Minister Dermot Ahern said it was "one of the most important human rights pieces of legislation the House had dealt with".
"Our society has changed substantially in recent decades,'' he said.
"While marriage is more popular than ever, other forms of relationships have become increasingly common; they create some difficulties in the legal system and require in our law a measure of recognition and of protection."
The bill was supported by all parties in the Dail, although individual politicians have criticised the legislation.
It is expected to become law in the autumn, 17 years after homosexuality was fully decriminalised in the Irish Republic.