|Provinces||Kayseri, Adana, Mersin|
|Districts||Aladağ, Karaisalı, Çukurova, Sarıçam, Seyhan, Yüreğir, Tarsus|
|- location||Aladağ, Adana, Turkey|
|- elevation||1,500 m (4,921 ft)|
|Mouth||Cape Deli, Mediterranean Sea|
|- location||Tarsus, Mersin, Turkey|
|Length||560 km (348 mi)|
|Basin||20,600 km2 (7,954 sq mi)|
The Seyhan River (formerly written Seihan, Sihun; ancient name: Σάρος, Sarus) is the longest river in Turkey that flows into the Mediterranean Sea. The river is 560 km and flows southwest from its headwaters in the Tahtalı-Mountains (in Sivas and Kayseri provinces) in the Anti-Taurus Mountains to the Mediterranean Sea via a broad delta. Its main tributaries are Zamantı and Göksu, which unite in Aladağ, Adana to form the Seyhan River. The Zamantı River originates from the Uzun Plateau in Pınarbaşı, Kayseri and crosses Tomarza, Develi and Yahyalı districts in Kayseri.
In ancient times, it was called the Sarus, and its plain was called the Cilician plain.
50 km from its mouth, Seyhan River flows through the city of Adana, the only settlement situated on the river. Several bridges and footbridges cross the river in Adana including the Stone Bridge, a 4th-century Roman bridge. The river meets the Mediterranean Sea at Cape Deli.
The major Seyhan Dam upstream of Adana serves for irrigation, hydroelectric power, and flood control. Yedigöze, Çatalan and Kavşak Bendi are the other dams on Seyhan River which also serve the same purposes. The river is currently under extensive development for hydroelectric power and irrigation.
- "Cumulative Impact Assessment Baseline Monitoring Report for the Goksu-Seyhan Hydropower Cascade" (PDF). EnerjiSA. February 2011. Retrieved 31 May 2013.