Recent ostracod assemblages of the Victoria marsh (Noja, Cantabria, N Spain) are described Twenty-two species have living representatives in this marsh. The strongly eurihaline species Loxoconcha elliptica dominates the assemblages, which is indicative of the estuarine character of the area. Taking into account the ecology of these species known from the literature, a zonal sketch of the different sub-environments is proposed for this transitional area. Fresh to oligohaline watérs are detected by the occurrence of continental species as Cypria ophtalmica, Cypridopsi's vidua and Pseudocandona spp. The estuarine influence is evidenced by the eurihaline character of species such L. elliptica and Cyprideis torosa. A coastal marine zone is characterised by the occurrence of more diversified assemblage with Aurila convexa, Aurila woutersi, Heterocythereis albomaculata, Pôntocythere elongata and Urocythereis oblonga, among others. Finally, the marine inner shelf influence is denoted by the presence of Basslerites berchoni, Bairdia sp., Carinocythereis sp. and Costa edwardsii. The distribution of biocoenotic as well as the thanatocoenotic individuals in the samples has been used to characterise indigenous and displaced waters inside this marsh