Faunistic note on the aquatic oligochaetes of the Geneva area and of Switzerland. Aquatic oligochaetes are used in Switzerland to assess sediment quality of watercourses and lakes. The aim of this note is to mention the presence of new species of aquatic oligochaetes for Switzerland and to update the inventory of this group in the Geneva area (Switzerland). Species diversity was studied in fine/sandy sediments of watercourses (canton of Geneva) and lakes (canton of Bern) as well as in very little studied environments in Switzerland, coarse surficial sediments and the hyporheic zone of watercourses (cantons of Geneva and Valais). Seven new species for Switzerland and twelve new species for the Geneva area were found. The number of taxa in the Geneva area is currently 81. The current development and use of molecular biology (barcoding, high-throughput sequencing technologies) as a tool for aquatic oligochaetes identification will allow researchers to improve significantly future species inventories.