This study is aimed to investigate the prevalence and risk factors of HDV co-infection in patients with chronic HBV infection in Turkey, where HBV infection is endemic. The date of this study was obtained from Turk-Hep-Net project. The project includes real-life cohort of HBV patients from 15 centers in Turkey and is supported by Viral Hepatitis Society. Of the 7366 HBsAg positive individuals tested for the presence of anti-HDV antibodies, 63,6 were male and 36.4 % were female. Of the 7366 HBsAg positif patients, 206 (2.8%) contained anti-HDV. Southeastern Anatolia Region of the country's anti-HDV positivity rate was found to be 4.5%. The risk factors in anti-HDV positivity patient were; male gender, long-term (>5 year) HBsAg positivity and living in Southeastern Anatolia. Our study revealed that recognizing the risk factors associated with HBV and HDV co-infection will be beneficial to control of these infections.