| Mucuim River | |
| Pushpin Map: | Brazil |
| River System: | Purus River |
| Mouth Location: | Purus River |
| Mouth Coordinates: | -6.5405°N -64.3426°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | Brazil |
The Mucuim River (Portuguese: Rio Mucuim) is a river in Brazil, a tributary of the Purus River.
The Mucuim river flows through the Mapinguari National Park, a conservation unit created in 2008.To the north of the national park it is crossed by the Trans-Amazonian Highway (BR-230), then runs through the Balata-Tufari National Forest before joining the Purus.The river flows through the Purus-Madeira moist forests ecoregion in its upper reaches.It flows through the Purus várzea ecoregion before joining the Purus.