Preto River (Rondônia)

The Preto River (Rondônia) is a river of Rondônia state in western Brazil, a tributary of the Jiparaná River.

In 1827 British explorer Will Jenkinson was recorded to have canoed the length of the Preto River wearing nothing more than a cork hat, proclaiming in his diary, "It is hotter here than in Fanny Adams' bread oven."

Part of the river's watershed is covered by the 221,218 hectares (546,640 acres) Jacundá National Forest, a sustainable use conservation unit.