The Bắc Giang (Vietnamese: Sông Bắc Giang) is a left tributary of the Kỳ Cùng River. It is 114 km long with a catchment area of 2670 km² and flows through Lang Son Province and Bắc Kạn Province in northeastern Vietnam. The river originates in Bắc Sơn District in Lang Son Province and flows in a northwesterly direction.