Epilithic algae are very important for sustainable aquatic ecosystems. It is also included in the group that should be examined in order to determine biodiversity in lotic ecosystems. For this purpose, this study has been carried out in the Hortuk, Moryayla Kan and camlikaya Streams, which are located in the Coruh Basin. The streams' altitude of (1730 - 2350 m.), depth of (13.0 - 45.6 cm.), water temperature of (8.21 - 9.80 degrees C), dissolved oxygen of (9.60 - 10.70 mg L-1 ) and pH values of (7.20 - 7.70) were determined. 28 taxa belonging to the Bacillarophyta group, including 22 species belonging to the Hortuk Stream, 20 species belonging to the Moryayla Stream, 14 species belonging to the Kan Stream and 6 species belonging to the camlikaya Stream, that are the important streams of the coruh Basin, were detected. Odontidium hymela (Roth) Kutz., and Hannaea arcus (Ehr.) R. M. Patrick were the most abundant species in epilitic composition. It was determined that the streams have oligotrophic character terms of epilithic diatom composition and diatom indices.