Dupax del Sur, officially the Municipality of Dupax del Sur, is a municipality in the province of Nueva Vizcaya, Philippines. At the 2020 census, it had a population of 21,224 people. The name Dupax came from the Isinay word "dopaj" which means "to lie down in complete relaxation and rest", the thing the natives wanted to do, upon repairing their camp and eating their catch, after hunting in the forest and before going homes.