The Gąsawa massacre (, literally "the Gąsawa crime") was a 1227 attack on a meeting of Polish Piast dukes which was being held near the village of Gąsawa in Kujawy, Poland. The High Duke of Poland, Leszek the White, was assassinated, and Duke Henry the Bearded of Silesia was gravely wounded. Because at the time of the attack some of the victims were bathing in preparation to retire for the night, the event is also known in Polish historiography as the Gąsawa Bloodbath (krwawa łaźnia w Gąsawie).