Anadyr (Ана́дырь) is a river in the extreme northeast of Siberia, Russia.

The river, taking its rise in the Stanovoi Mountains as the Ivashki or Ivachno, about 67°N latitude and 173°E longitude, flows through the Chukotka, at first southwest and then east, and enters the Gulf of Anadyr after a course of about 500 miles. The country through which it passes is thinly populated, and is dominated by tundra, which is rich with a variety of plant life. Much of the region is folded in rugged mountains, and is a beautiful landscape. For nine months of the year the ground is covered with snow, and the frozen rivers become navigable roads. Reindeer, upon which the inhabitants subsist, were once found in considerable numbers, but the domestic reindeer population has collapsed dramatically since the reorganization and privatization of state-run collective farms beginning in 1992. As herds of domestic reindeer have declined, herds of wild caribou have increased.

See also: Anadyr (town), Operation Anadyr