In Argentina, marriage is allowed between a man and woman. However, starting in 2003, the Autonomous City of Buenos Aires and the province of Río Negro offered the possibility of civil unions, which are private contracts between two responsible adults (opposite-sex and same-sex couples) who have lived together for at least two years. These couples are granted some of the rights provided to married couples.
The civil union gives both members of the couple health and insurance benefits and hospital visitation rights, but do not allow same-sex couples to receive inheritance, the possibility to marry, or the right to adopt children.
At a national level, Argentina extends widow/widower pensions to surviving partners of same-sex couples. Four Argentine labor unions have now extended National Security System medical benefits to employees’ same-sex partners. The unions and the system operate jointly in the health-care arena. The benefits are available to members of the unions for teachers, commerce employees, executives and air-transport personnel. In December, 2005 a judge in Argentina agreed and ordered jails and prisons across the province to authorize conjugal visits for all gay prisoners. The ruling also allows inmates who develop relationships inside jails also to be allowed sexual relations.
http://en.wikipedia.org/wiki/Civil_unions_in_Argentina