The present study aimed a floristic survey of aquatic macrophytes in four water supply reservoirs (Iraí, Passaúna, Piraquara I and II) of the Iguaçu River basin, Paraná, Brazil. Sampling and herborization of biological material followed methods described in literature. The species were classified by life forms. We found 90 species in 57 genera and 36 families, were 52.7% are monospecific. The richest reservoir was Passaúna (40 spp.), followed by Iraí, Piraquara I and Piraquara II (36 spp. each). Cyperaceae was the most representative with 17 spp., followed by Asteraceae, Onagraceae and Polygonaceae (7 spp. each). Amphibious and emergent life forms were equally express throughout species (41% each). Since aquatic macrophytes structure and contribute to environment biodiversity, the present study can assist management and implementation of biodiversity conservation efforts.