| Ratnyčia | |
| Mouth Coordinates: | 54.0167°N 81°W |
| Subdivision Type1: | Country |
| Length: | 33km (21miles) |
| Discharge1 Avg: | 1.31m3/s |
| Basin Size: | 172km2 |
Ratnyčia is a river in southern Lithuania.
It begins near the state border of Lithuania and Belarus, in the Dainava Forest, in a swamp.