| Astarachay | |
| Name Other: | Astaraçay, آستاراچای |
| Subdivision Type1: | Countries |
| Subdivision Name1: | Iran and Azerbaijan |
| Subdivision Type2: | Province |
| Subdivision Name2: | Gilan, Iran |
| Subdivision Type3: | District |
| Subdivision Name3: | Astara, Azerbaijan |
| Subdivision Type5: | Cities |
| Subdivision Name5: | Astara, Iran Astara Azerbaijan |
| Length: | 38km (24miles) |
| Mouth: | Caspian Sea |
| Basin Size: | 242km2 |
The Astarachay (Ostororü|script=Latn, Persian: آستاراچای, Azerbaijani: Astaraçay), is a small river that defines the eastern border between Iran and Azerbaijan in Western Asia.[1]
The river discharges into the Caspian Sea. After flowing in a canyon through the Alborz mountain range, it reaches its river mouth on the southwestern Caspian coast.
The Astarachay is partially in Gilan Province of far northwestern Iran.