The Great Yenisey (Russian: Большой Енисей Bolshoy Yenisey; Tuvan: Бии-Хем, romanized: Pî-Xem) is a river in the Republic of Tuva, the right source of the Yenisey, at its confluence with the Little Yenisey.

The name Bii-Khem in Tuvan means "big river".

The length of the Great Yenisey is 605-kilometre (376 mi), its basin area is 56,800-square-kilometre (21,900 sq mi). The river is navigable for 285-kilometre (177 mi) from the mouth. It flows out of Lake Kara-Balik. High water level of the river is due to the fact that the catchment area of the river includes the Todzha Basin, which relief forms a wide catchment area. The river receives numerous tributaries, the largest of them are right Toora-Khem, Khamsara, Systyg-Khem. The basin of the Bolshoy Yenisey is a mountainous region, which borders in the north and east are the administrative boundaries of Tuva with Buryatia, Irkutsk Oblast and Krasnoyarsk Krai. The river flows through the Tuva basin in its lower course. Near the city of Kyzyl it joins the Kaa-Hem, forming the Ulug-Khem, which is actually the beginning of the Upper Yenisey. The whole Todzhinsky District of the Republic of Tuva is located in the basin of the river, its centre, Toora-Khem, is located at the confluence of the Toora-Khem tributary.

The upper course of the river is virtually untouched virgin territory, with the Azas Plateau, including nine extinct volcanoes with unique geological features. A beautiful lake Azas (its other name is Todzha) is located on the Toora-Khem tributary, the lake is one of the tourist sites of the Republic. Almost the entire lake and the area of the river are included in the Azas Federal Reserve.

• List of rivers of Russia

• Fishing in Russia