Cuyuni-Mazaruni is one of the ten regions in which the republic of Guyana is administratively divided. It owes its name to the Cuyuni and Mazaruni rivers. Bordered on the north by Barima-Waini, the Essequibo-Demerara Occidental and Pomeroon-Supenaam Islands, to the east by Alto Demerara-Berbice, to the south by Potaro-Siparuni and Brazil, and to Venezuela to the west, the latter country claims this territory as part of of the Bolívar State inside the call Guayana Esequiba. Its capital is Bartica, being other localities of importance Issano, Isseneru, Kartuni, Peters Mine, Arimu Mine, Kamarang, Keweigek, Imbaimadai, Tumereng and Kamikusa. Its current extension is 47,213 km².
Until the 1980 constitution, with which it received its current status as an independent administrative body, most of its territory had belonged to the territorial entity called Mazaruni-Potaro. As a territorial body with some independence it has its own legislative and executive powers, as well as a representative in the National Assembly of Georgetown, and two members in the National Congress of the National Democratic Bodies.