The species diversity of Clitellata (a group of annelid worms) is described for three river systems in different parts of southern Sweden. The water of one river (Säveån) discharges into the harbour of Göteborg on the Swedish west coast, that of the other two rivers (Svartån and Kilaån) into the Baltic Sea. A total of 143 species, representing the taxa Enchytraeidae (61), Propappidae (1), Lumbricidae (15), Lumbriculidae (6), Tubificidae (4 Rhyacodrilinae, 33 Naidinae, 13 Tubificinae), and Hirudinida (10), are reported. Of these, 24 enchytraeids and six lumbricids were found only in the riparian zone, i.e., in the semiaquatic habitats of the river banks. Six species of Enchytraeidae could not be assigned to any known species and are likely to be new to science. In addition, the following species are recorded from Sweden for the first time : Achaeta brevivasa, Fridericia benti, F. healyae, F. lenta, F. sylvatica, Oconnorella tubifera (all Enchytraeidae), Aporrectodea limicola (Lumbricidae), Stylodrilus brachystylus (Lumbriculidae), Dero dorsalis, Nais behningi, Haber speciosus, and Peipsidrilus ?saamicus (all Tubificidae). Overall, the species composition is typical of today’s fauna of the once glaciated Northern Europe, but for the family Enchytraeidae, the biogeographical affinity of Sweden is stronger with Denmark and Germany than with, e.g., the British Isles and the eastern parts of Central Europe.