The genus Aphanolaimus is composed of a number of species of which two occur in the Netherlands. Two other species have been described from Belgium in 1983. We assume that the species described from Belgium, also occur in the Netherlands but the Dutch material, present in the Wageningen nematode collection, has not been studied in detail after 1983. Aphanolaimus species occur in freshwater and wet soils. It are relatively small nematodes but easy to recognize by their annulated cuticle, long setae around the small mouth cavity and large amphids, just behind the setae. Although direct evidence is lacking, we assume that they consume bacteria.