The species diversity of Clitellata (a group of annelid worms) is described for three river systems in different parts of southernSweden. The water of one river (Säveån) discharges into the harbour of Göteborg on the Swedish west coast, that of theother 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), andHirudinida (10), are reported. Of these, 24 enchytraeids and six lumbricids were found only in the riparian zone, i.e., in the semiaquatichabitats of the river banks. Six species of Enchytraeidae could not be assigned to any known species and are likely tobe new to science. In addition, the following species are recorded from Sweden for the first time : Achaeta brevivasa, Fridericiabenti, 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 (allTubificidae). Overall, the species composition is typical of today’s fauna of the once glaciated Northern Europe, but for the familyEnchytraeidae, the biogeographical affinity of Sweden is stronger with Denmark and Germany than with, e.g., the British Islesand the eastern parts of Central Europe.