The Ceyhan River basin consists of a large number of rivers, lakes and dams and since the basin area is important for agricultural and industrial activities, it receives an extensive discharge of pollutants. There is a possibility that toxic (e.g. some cyanobacteria) and pathogenic, such as Salmonella species, bacteria present in the bacterial community. Therefore these bacteria could be responsible for water quality and the health diseases of the aquatic organisms. In this study the epiphytic bacterial densities on different submersed species, collected from Ceyhan River Basin, in different seasons have been compared. The impacts of physico-chemical variables of the surrounding water on epiphytic bacteria population has also been tested. Average densities of bacteria on the leaves of all tested plants were higher in autumn and lower in spring. In all seasons, the density of bacteria on the leaves of Myriophyllum spicatum was higher than that of the other two species, Ceratophyllum demersum and Groenlandia densa. Bacterial density on the leaves of all tested plants significantly differed between the season. Epiphytic bacterial density correlated significantly with pH, conductivity and NO3 – . On the other hand, epiphytic bacterial density was strongly correlated with temperature, TN, NH4 +, TP, SRP and Chl a, while no significant correlation could be determined between bacterial population and DO.