Kasagh (Armenian: Քասաղ) is a river in the west-central region of modern Armenia which flows north to south. It originates near Mount Aragats in Aragatsotn province, flows south into Armavir province and into the Metsamor, which itself is a tributary of the Aras.

From north to south:

• the town of Aparan
• the Aparan reservoir
• Saghmosavank, an Armenian monastic complex
• Hovhannavank, a 13th-century Armenian monastic complex
• the town of Ashtarak
• the town of Oshakan
• the city of Vagharshapat

• List of lakes of Armenia
• Geography of Armenia