The Siletz River flows about 67 miles (108 km)[3] to the Pacific Ocean through coastal mountains in the U.S. state of Oregon.

Formed by the confluence of its north and south forks near Valsetz in Polk County, it winds through the Central Oregon Coast Range.

For parts of its course along its upper reaches, the river flows near non-contiguous parcels of land belonging to the Siletz Reservation.

After another sharp turn to the west 25 miles (40 km) from the mouth, the river flows by Jack Morgan County Park and receives Chitwood, Hough, and Wade creeks, all from the right.

It receives Roots, Skalada, Townsend, and Stemple creeks in quick succession, all from the right, near RM 15 (RK 24).

Turning north and then west again, the river over the next 5 miles (8 km) receives Bear, Skunk, Barhaven, and Anderson creeks, all from the right.

Sport fish include fall chinook salmon, summer and winter steelhead, and coastal cutthroat trout.