Potential factors affecting the occurrence of filamentous algae include the morphometry of water bodies, the type of substrate and physicochemical conditions of the habitat. This study attempts to describe the individual filamentous algae species recorded in Poland, taking into account the trophic and ecological characteristics based on our own research and available literature data. Filamentous algae attached to the substrate as well as those forming free-floating patches (loose or dense mats) and crusts occur in all types of water bodies. Among the representatives of filamentous algae species,