| Astarachay | |
| Astaraçay, آستاراچای | |
| River | |
| Country |  Iran and  Azerbaijan | 
|---|---|
| Provinces | Gilan  Iran | 
| District | Astara  Azerbaijan | 
| Cities | Astara  Iran, Astara  Azerbaijan | 
| Mouth | Caspian Sea | 
| Length | 38 km (24 mi) | 
| Basin | 242 km2 (93 sq mi) | 
Coordinates: 38°15′N 48°31′E / 38.25°N 48.52°E
The Astarachay (Persian: آستاراچای, Azerbaijani: Astaraçay), is a small river that defines the eastern border between Iran and Azerbaijan in Western Asia.
It is a tributary of the Caspian Sea. After flowing in a canyon through the Alborz mountain range, it reaches its river mouth on the southwestern Caspian coast.
It is partially in Gilan Province of far northwestern Iran.