Diatoms are mostly characterized by their siliceous bipartite cell walls, forming a frustule. Diatoms are one of important groups for monitoring in lentic and lotic systems. Cymbelloid diatoms are one of the highest diversity in Turkish inland waters. In this study, the samples were collected from 25 stations from different habitats (epilithic, epipelic and epiphytic) in Yalova. As a result, 19 taxa belonging to the genera Cymbella, Cymbopleura, Encyonema, Encyonopsis and Reimeria were found in the study area and Cymbella excisa, Cymbopleura cf. lange-bertalotii, Encyonema reichardtii, Encyonopsis minuta, E. subminuta and Reimeria ovata were recorded as "new record" for Turkish freshwater diatom flora.