The San Guillermo National Park at an altitude of 3'000 - 6'000 m covers an area of 1'600 square kilometres and is located in the northern part of the San Juan Province. The park, established in 1998, is the core of the San Guillermo Biosphere Reserve, which encompasses almost 10'0000 square kilometres. The San Guillermo National Park protects the largest coexisting populations of guanacos and vicuñas.
Argentina 1999, San Guillermo National Park.
The stamp was issued in the series "National Parks IV".