The Ji-Paraná River (Machado River), sometimes spelled Jiparaná, is a river in Rondônia state in western Brazil. It is a tributary of the Madeira River in the Amazon Basin. For much of its length it runs roughly parallel with the northeastern state border of Rondônia. The city of Ji-Paraná is divided by the river. Part of the river's basin is covered by the 221218 ha Jacundá National Forest, a sustainable use conservation unit. Part of the basin is in the 346861 ha Jaru Biological Reserve, a fully protected conservation unit created in 1984. The river forms the southern boundary in Rondônia of the Campos Amazônicos National Park, a 961318 ha protected area created in 2006 that holds an unusual enclave of cerrado vegetation in the Amazon rainforest.