A study of a collection of freshwater sponges of Venezuela (South America) was made, 17 species were identified, belonging to tree families (Spongillidae, Potamolepidae and Metanidae): Spongilla alba, S. spoliata, Trochospongilla gregaria, T. paulula, T. minuta, Saturnospongilla carvalhoi, Corvoheteromeyenia heterosclera, Uruguaya corallioides, Oncosclera navicella, O. spinifera, O. intermedia, Metania reticulata, Acalle recurvata, Drulia browni, D. cristata, D. uruguayensis and D. conifera. Morphological characteristics, habitat and distribution in Venezuela of each species are given. A taxonomic key to the freshwater sponges of Venezuela hitherto known is presented. The fauna of the Orinoco River basin contains 15 species and is very similar to those of the Amazon River. S. alba has been found only in the estuarine waters of Maracaibo Lake and C. heterosclera in the Unare River basin. The proposition of a passive invasion of the freshwater habitat by marine sponges is additionally presented in detail. Description of habitats, morphology, life history, reproduction, importance, collection and preparation of freshwater sponges samples are presented. Scanning electron photomicrographs of C. heterosclera are used to clarify the morphology and fine structures of a freshwater sponge.