| Gregório River | |
| Pushpin Map: | Brazil |
| Source1 Location: | Acre |
| Mouth Location: | Eirunepé, Amazonas |
| Mouth Coordinates: | -6.8159°N -70.6424°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | Brazil |
| Length: | [1] |
The Gregório River (Portuguese: Rio Gregório is a river of Amazonas and Acre states in western Brazil. It is a tributary of Juruá River.
The Gregório River runs in a northeast direction through the Brazilian states of Acre and Amazonas. It has a length total of 350 km.[2] In Acre between the BR-364 highway and the Amazonas border the river forms the boundary between the Rio Gregório State Forest to the east and the Mogno State Forest to the west, two sustainable use conservation units created in 2004.Across the border in Amazonas the river runs through the Rio Gregório Extractive Reserve, which protects 80% of the sources of the river.