A survey of the actual brackish-water malacofauna of Belgium is presented. Two regions have been investigated: a) the coastal area and b) the Belgian part of the Western Scheldt, downstreams of Antwerp. The following species were recorded: Hydrobia ulvae, Hydrobia ventrosa, Potamopyrgus antipodarum, Assiminea grayana, Alderia modesta, Limapontia depressa, Ovatella myosotis, Leucophytia bidentata and Cerastoderma glaucum . Tergipes tergipes, Tenellia adspersa and Eubranchus sp., three species which are known from literature, could not be rediscovered during the present investigation. On the other hand, a current revision of Hydrobia ventrosa from the collections of the K.B.I.N., has shown that Semisalsa stagnorum at least once belonged to the Belgian fauna. Whether this is still the case nowadays, remains to be demonstrated.