The Hueang River (Thai: แม่น้ำเหือง, RTGS: Maenam Hueang, Thai pronunciation: [mɛ̂ːnáːm hɯ̌əŋ]) is one of the boundary rivers between Thailand and Laos. It originates in the hills of Na Haeo district, Loei Province. Outing there, it flows through Dan Sai, Phu Ruea, Tha Li districts and mouths to the Mekong River in Chiang Khan district, Loei Province. It is 110 kilometres (68 mi) long, of which 90 kilometres (56 mi) form the boundary.