| Plesná | |
| Subdivision Type1: | Countries |
| Subdivision Type2: | Region (CZ) |
| Subdivision Name2: | Karlovy Vary |
| Subdivision Name3: | Saxony |
| Mouth Location: | Ohře |
| Mouth Coordinates: | 50.1125°N 12.4642°W |
The Plesná (German: Fleißenbach) is a river of the Czech Republic (Karlovy Vary Region) and Germany (Saxony). It is long and it is a tributary of Ohře. Its source is located near Horní Paseky, on the southern slope of the Stráž mountain in the Fichtel Mountains. It crosses the Czech-German border into Germany and then re-enters the Czech Republic near Bad Brambach. Its confluence with Ohře lies southwest of Nebanice.