Iguassu Falls (Portuguese: Cataratas do Iguaçu, Spanish: Cataratas del Iguazú IPA [iɣwa'su]) are waterfalls of the Iguaçu River located on the border of the Brazilian state of Paraná (in the Southern Region) and the Argentinian Province of Misiones.

The Falls are shared between the Iguazú National Park (Argentina) and Iguaçu National Park (Brazil). The parks were designated UNESCO World Heritage Sites in 1984 and 1986 respectively.

Most of the falls are within Argentinian territory, but from the Brazilian side a more panoramic view is obtained.

The falls are located near the following cities:

* Foz do Iguaçu, a major city located in the Brazilian state of Paraná
* Puerto Iguazú, a city located in the Argentinian province of Misiones.

The name comes from the Guarani words í (water) and guazú (big).