On 22 July 1997, Sandri was appointed Apostolic Nuncio to Venezuela and Titular Archbishop of Aemona by Pope John Paul II. He received his episcopal consecration on the following 11 October from Cardinal Angelo Sodano, with Cardinal Aramburu and Archbishop Giovanni Battista Re serving as co-consecrators, at St. Peter's Basilica. He selected as his episcopal motto: ""Ille Fidelis"", meaning, "He (Christ) remains faithful" (). He was the first Argentinian to hold the title of Apostolic Nuncio. After two years in Venezuela, he was named Apostolic Nuncio to Mexico on 1 March 2000. During his brief tenure there he was tasked with restraining the Mexican bishops from intervening in political affairs.