| Conflict: | Siege of Opochka |
| Partof: | Fourth Muscovite–Lithuanian War |
| Date: | 20 September - 18 October 1517 |
| Place: | Opochka fortress |
| Coordinates: | 56.7119°N 28.6564°W |
| Result: | Russian victory[1] |
| Combatant1: | Grand Duchy of Lithuania Kingdom of Poland |
| Combatant2: | Grand Duchy of Moscow |
| Commander1: | Konstanty Ostrogski Jerzy Radziwiłł |
| Commander2: | Vasily Morozov-Saltykov |
| Strength1: | 14,000 |
| Strength2: | Unknown |
| Casualties1: | About 5,500 |
| Casualties2: | Unknown |
The siege of Opochka was an unsuccessful attempt by the Grand Duchy of Lithuania and the Kingdom of Poland to conquer the Russian fortress of Opochka during the Fourth Muscovite–Lithuanian War.