Objectives: To investigate the distribution of hepatitis B virus (HBV) genotypes among patients with chronic hepatitis B in Kayseri, Turkey. Methods: The study took place in the Department of Microbiology, Erciyes University, Kayseri, and Iontek Laboratory, Istanbul, Turkey, from January 2005 to October 2007. One hundred and ten patients with chronic hepatitis B were included in this study. Hepatitis B virus DNA in sera were investigated by using the real-time polymerase chain reaction. Viral DNA was extracted from 200 mu L of serum using the QIAamp DNA minElute kit (Qiagen, Hilden, Germany). Reaction mixture was prepared by Fluorion HBV QNP 2.0 (Iontek, Istanbul, Turkey). Results: Genotype D was detected in 107 of 110 (97.2%) patients, however, genotyping failed in 3 patients (2.7%). No other genotypes were found. Conclusion: The vast majority of Turkish patients with chronic hepatitis B have genotype D.