| Wisznia | |
| Name Other: | Ви́шня |
| Mouth Location: | San |
| Mouth Coordinates: | 49.9458°N 22.8742°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | Poland, Ukraine |
Wisznia (Vyshnia, Ви́шня, in Ukrainian) is a right tributary of the San River in southeastern Poland.
It flows for 100km (100miles), 85km (53miles) of which flows through Ukraine. Just south of Rudky, Ukraine, near the village of Novosilky-Hostynni, the river reverses flow, with the southern extremity flowing into the Dniester.
The river falls into San near the city of Radymno.