-To understand the distribution and ecological characteristics of non-marine ostracods, the Poisson Method was applied to a total of 41 taxa (26 recent and 15 sub-fossil) from 111 (out of 120) aquatic bodies of Adyaman Province, Turkey. All taxa were new records for the area and Schellencandona insueta and Gomphocythere n. sp. were the first records for Turkey. According to the Poisson method, ostracods were randomly distributed among all sampling sites (P > 0.05). This is especially true for the cosmopolitan species (Candona neglecta, Heterocypris incongruens, Ilyocypris bradyi and Psychrodromus olivaceus) with broader ecological tolerance ranges to different environmental variables. According to canonical correspondence analysis (CCA), the first two axes explained 77.4% of the relationships and the most effective variables were found as electrical conductivity (F = 3.987, P = 0.002, l = 0.31), water temperature (F = 3.582, P = 0.002, l = 0.17), pH (F = 3.510, P = 0.002, l = 0.12) and elevation (F = 4.491, P = 0.02, l = 0.37). Additionally, the ratio (numbers of taxa/site = 2) was found same at lower (450-550 m) and higher (1359-1459 m) ranges, in which H. incongruens and I. bradyi were the most common species found from different habitats. Overall, random distribution of ostracods among sampling sites seemed to be more affected by random distribution of cosmopolitan species at the regional level than the non-cosmopolitans whose distribution may be uniform or clumped since they prefer certain types of ecological conditions at local level.