La Matanza ('The Slaughter' in Spanish) is a partido (county or department) located in the urban agglomeration of Greater Buenos Aires, Buenos Aires Province, Argentina.

This provincial subdivision had 1,775,272 inhabitants (at the 2010 Census)[1] in an area of 325.71 km2 (125.76 sq mi).

Is believed to reference a confrontation that Diego, the brother of conquistador Pedro de Mendoza, had with the Querandí tribe in 1536,[2] where he and 22 soldiers that were with him died.

The oldest document in which the name of La Matanza appears is dated 29 July 1603.

In the 20th century, its population dramatically increased with the influx of the European immigration first and the internal migration later to the surroundings of the City of Buenos Aires, followed by migrants from neighbouring countries (mainly Bolivia and Paraguay)[4] by the end of the century.