In this study, red mark syndrome (RMS) in rainbow trout was confirmed for the first time in Turkey. The disease occurred in market size rainbow trout (250-300g) reared in raceways at a water temperature of 11 degrees C in the Mediterranean region of Turkey in February 2014. The affected fish showed scale loss, followed by a haemorrhagic dermatitis, with oval lesions perpendicular to the lateral line. The lesions were bright red, usually raised, non-ulcerative, approximately 5 cm in length and typically on the flank on the fish. Histopathologically, an inflammatory response was determined in the dermis. The fish were in good condition, showed normal behaviour and there was no increased mortality associated with the disease. Samples for bacteriological examinations were collected from the anterior kidney, liver, spleen and skin lesions using sterile swabs. These samples were streaked onto trypticase soy agar plates and incubated 22 degrees C for 48 h. Bacterial growth was not observed on the plates.