伊瓜苏瀑布（葡萄牙语：Cataratas do Iguaçu，西班牙语：Cataratas del Iguazú，当地的瓜拉尼语意为“大水”）是由位于巴西巴拉那州和阿根廷边界上的伊瓜苏河从巴西高原辉绿岩悬崖上落入巴拉那峡谷形成的瀑布。现时成为联合国世界自然遗产的一部分。

伊瓜苏瀑布与东非维多利亚瀑布及美加的尼亚加拉瀑布是世界三大瀑布。伊瓜苏瀑布实为一组瀑布群，由275股大小瀑布或急流组成，总宽度4公里，比尼亚加拉瀑布宽4倍，落差由平均60公尺至最高82公尺。年均流量1,750立方米/秒，雨季时瀑布最大流量为12,750立方米/秒，这时大小飞瀑也汇合成一个马蹄形大瀑布。

Iguazu Falls, Iguazú Falls, Iguassu Falls, or Iguaçu Falls (Spanish:Cataratas del Iguazú [kataˈɾatas ðel iɣwaˈsu]; Guarani:Chororo Yguasu [ɕoɾoɾo ɨɣʷasu]; Portuguese:Cataratas do Iguaçu [kataˈɾatɐʒ du iɡwaˈsu]) are waterfalls of the Iguazu River on the border of the Argentine province of Misiones and the Brazilian state of Paraná. The falls divide the river into the upper and lower Iguazu. The Iguazu River rises near the city of Curitiba. For most of its course, the river flows through Brazil, however, most of the falls are on the Argentine side. Below its confluence with the San Antonio River, the Iguazu River forms the boundary between Argentina and Brazil.