Since their introduction in 1935, cane toads (Rhinella marina (Linnaeus, 1758)) have established and spread throughout north and north-eastern Australia. Cane toad impacts on terrestrial ecosystems are well documented, but impacts on aquatic ecosystems are less well known. We investigated the diet of cane toads collected from warm Great Artesian Basin-fed springs on Edgbaston Reserve in central Queensland, Australia. A higher proportion of aquatic invertebrates to terrestrial invertebrates was found amongst their alimentary canal contents. Aquatic taxa consumed included molluscs (Gastropoda), insects (Coleoptera) and crustaceans (Amphipoda). Given this diet, the presence of cane toads at Edgbaston Springs, and the high endemicity of the aquatic biota of these springs, we conclude that R. marina present a threat to the conservation of desert spring ecosystems.