Objective: We determined the seroprevalence of HBV and HCV before endoscopic procedures and assessed transmission of hepatitis B and C viruses during endoscopic procedures. Materials and Methods:In total, 2690 consecutive participants who underwent upper gastrointestinal endoscopy under the Early Diagnosis of Gastric Cancer Pilot Project were enrolled in this study. Their medical records, demographic properties, and endoscopic diagnoses were reviewed. HBsAg and anti-HCV serology of all participants was examined before endoscopic procedures. Results:The seroprevalence of HBS(+) was 2.7% and of HCV(+) was 0.2%. The prevalence of HBV infection indicated intermediate endemicity. HCV(+) rates were higher in participants who had undergone endoscopy previously (p = 0.020). Conclusion:Pre-endoscopy determination of hepatitis serology of patients is beneficial to avoid transmission of hepatitis B and C viruses