A systematic account is given of the aquatic gastropod fauna of the lower Okavango River in Namibia and Botswana, and of the East Caprivi area in Namibia, based on collections made mostly in 1983–86 from about 100 different sites. A total of 20 living species are reported, 9 of them for the first time from this area: Bellamya monardi, Lobogenes michaelis, Cleopatra elata, Afrogyrus coretus, Segmentorbis angustus, S. kanisaensis, Bulinus scalaris, B. depressus and B. tropicus. All are found outside this area and most are widely distributed Afrotropical species. Some do not occur farther south than the Okavango Delta, while others reach a south-western limit here but occur at greater latitude in the eastern tropical corridor on the coast of Natal. Bulinus globosus and Biomphalaria pfeifferi occur throughout the study area and are intermediate hosts for schistosome parasites of man and livestock.