Brazil's Supreme Court voted Thursday to allow gay couples in "stable partnerships" many of the same rights as heterosexual married couples.
The decision was hailed as a landmark case in a country with the world's largest population of Roman Catholics.
It was approved by 10-0 with one abstention, BBC reports.
"Those who opt for a homosexual union cannot be treated less than equally as citizens," Justice Camen Lucia said, as reported by AFP.
"No one should be deprived of rights on the basis of sexual orientation," added Justice Ricardo Lewandowski.
The ruling means that judges now cannot deny rights like retirement benefits, inheritance, health benefits and adoption to gay couples, said gay advocates.
Brazil is now one of the few South American countries that recognize gay partnerships and grant gays many rights and benefits similar to those given to straight couples. Argentina also allows gay partnerships, Reuters reports.
Gay activists welcomed the ruling as a "historic day" for the country, BBC reports.
The ruling, however, does not recognize gay marriage, which would include public or religious ceremonies, it states.
Brazil's Roman Catholic Church has opposed gay civil unions.