| Piyain River | |
| Image Alt: | Piyain River in Sylhet |
| Subdivision Type1: | Countries |
| Subdivision Name1: | India, Bangladesh |
| Subdivision Type2: | District |
| Subdivision Name2: | Sylhet |
| Source1 Location: | Umgat river of Assam |
| Mouth Location: | Surma River |
Piyain River a trans-boundary river of India and Bangladesh.[1] It is a tributary of the Surma river, which is originates from the Umngot of Meghalaya. The river enters Bangladesh through Sylhet district.
The length of the river is 145 km. Piyain river has emerged from the river om or Umagat river or Assam.[2]