Zayul County(Tibetan: རྫ་ཡུལ་རྫོང) or Zayü (Chinese: 察隅县) is a county in the Nyingchi Prefecture in the southeastern part of the Tibet Autonomous Region, China.
The historical Zayul region is marked by the basin of the Zayul River, with its two branches: Rongto Chu (or the western Zayul River) and Zayul Chu (or the eastern Zayul River). The two branches join near the town of Rima. After the junction, the Zayul river enters India's Arunachal Pradesh where it is called Lohit.