Kamil Abdus (Balik) Lagoon, a coastal lagoon located in the Sea of Marmara (Turkey), is threatened by human activities, as are many of the aquatic habitats in Turkey. The supplying of new knowledges for biodiversity conservation from threatened habitats is quite important for the conservation of them. The lagoon's species composition, and their temporal and spatial distribution, diversity, and dominance were investigated and the results were correlated with the environmental variables. As shown in the analyses (Spearman's correlation, CCA), distribution of ostracod species are associated with salinity values. Twenty-one ostracod species were identified from the four stations sampled between February 2016 and January 2017 in Kamil Abdus Lagoon (Istanbul, Turkey). The most abundant species were determined as Cyprideis torosa, Aurila arborescens, Loxoconcha rhomboidea, Xestoleberis communis, and Xestoleberis aurantia. The ostracod fauna in Kamil Abdus Lagoon include 13 species of littoral to sublittoral/phytal marine forms, one brackish (euryhaline) form (Cyprideis torosa), and six halophilic freshwater continental forms. The results show that the physico-chemical conditions and morphologic structure of the lagoon has to be protected with last status and highlighted the need of strong policies for wetlands protection. We believe that our results concerning the ostracod ecology in Turkey lagoons can be of use for understanding of changes in enviromental conditions.