The vegetative characters — especially those which are important for identification of the species — together with the distribution of the Polysiphonia species occurring in Netherland’s waters were subject of the following study. The material used consisted for the greater part of dried specimens, present in the following collections: Rijksherbarium (Leiden), herbarium Van Goor, Zoological Station (Den Helder), herbarium of the “Koninklijke Nederlandse. Botanische Vereniging” (Rijksherbarium, Leiden) and the herbaria of the Universities of Amsterdam, Groningen and Utrecht.