Barguzinsky Nature Reserve is the oldest of nature reserves. It is located in Buryatia (Russia) on the west slope of the Barguzin Range, including the northeast shores of the Lake Baikal and a part of the lake itself. The name of the preserve (and the range) comes from the Barguzin River.

The area of the reserve is 2,482 km2 (958 sq mi). It was created in 1916 to preserve and increase the numbers of Barguzin Sable (Martes zibellina). Mountainous and taiga landscapes are also being preserved. The Barguzin Nature Reserve is inhabited by elks, musk deer (known as kabarga), brown bears, Black-capped Marmots, grouse, etc. Omuls, sigs, sturgeons, graylings, taimens, lenoks and other fish spawn in the rivers of the reserve.