Reserva natural Sierra del Tigre, Natural reserve in Buenos Aires Province, Argentina.

Reserva natural Sierra del Tigre is a protected natural area in the Tandilia mountain range of Buenos Aires Province, Argentina. It covers open grasslands and shrubland typical of the pampa region, set across a hilly landscape of low rocky ridges.

In 1972, geographer Huberto Cuevas Acevedo founded the Friends of Sierra del Tigre Natural Reserve group, which led directly to the area receiving official protection in 1973. Before that, the hills had been used for generations as a working quarry zone.

The stone paths and old dwellings in the reserve were built by the picapedreros, the quarrymen who worked these hills before the area became a reserve. The reserve's creation was pushed by geographer Huberto Cuevas Acevedo through the Agrupación Amigos de la Reserva Natural de la Sierra del Tigre, founded on 30 October 1972.

A consolidated path runs through the area and is open to walking, horseback riding, and vehicles, making the terrain accessible for different kinds of visitors. Sturdy footwear and layers of clothing are a good idea, as conditions in the hills can change quickly.

The 22-hectare core holds the biological station, where species are bred to restock the reserve, and the interpretation centre. The rest of the 150 hectares is former quarry land, so old stonecutters' houses and stone paths remain among the pits.