Chicken War or Hen War (Polish: Wojna kokosza) is the colloquial name for a 1537 anti-royalist and anti-absolutist rokosz (rebellion) by the Polish nobility.
The derisive name was coined by the magnates, who for the most part supported the King and claimed that the conflict's only effect was the near-extinction of the local chickens, which were eaten by the nobles gathered for the rokosz at Lwów, in Ruthenian Voivodeship.