The Roman Catholic Diocese of Zárate-Campana is a Latin rite suffragan diocese in the ecclesiastical province of the Archdiocese of Mercedes-Luján, in central Argentina on the Atlantic coast, having had a change of metropolitan from La Plata in 2019.

The Archdiocese of Mercedes-Luján is a Latin Church ecclesiastical territory or archdiocese of the Catholic Church in north-central Buenos Aires Province, Argentina. It was immediately subject to the Holy See, coming into 2019. Erected as the Diocese of Mercedes on 20 April 1934, it was renamed as the Diocese of Mercedes-Luján on 10 May 1989 and elevated to its status as an archdiocese on 21 November 1997. Its mother church is the Catedral Basílica de Mercedes-Luján in Mercedes.