The article presents the results of the observations regarding the algal flora from 57 water bodies in the largest hydrographic basin in Romania – that of the Siret River. Samples were taken for algological analysis (phytoplankton, periphyton, microphytobenthos) from rivers, dam reservoirs, fishponds etc. During the research period (1965-2013) a total of 941 species of algae were identified, of which 278 are novelties for the algoflora of this river basin. The highest share – as number of species – has been achieved by diatoms (340 species), followed by green algae (237 species).
