AIM: To investigate the epidemiology of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection in the two major ethnic groups in Kazakhstan. METHODS: A cross-sectional prospective study of HBV and HCV seroprevalence was performed among individuals born in Kazakhstan with no history of chronic hepatitis or liver disease. RESULTS: There were 290 volunteers (140 Russians and 150 Kazakhs) aged 10 to 64 years, males accounted for 46%. Active HBV infection (HBsAg positive) was present in 3.8%, anti-HBc in 30%. The prevalence was similar in females and males (33% vs 25%) (P = 0.18). The prevalence of anti-HBc increased from 19% in 10-29 years old volunteers to 53% in 50-years and older volunteers. The prevalence of HBV infection was higher in married than in single adults (38% vs 26%, respectively) (P = 0.2) and more common in Kazakhs (35%) than in Russians (24%) (P = 0.07). HCV infection was present in 9 subjects (3.2%), 5 of them also were positive for anti-HBc in the absence of HBsAg. CONCLUSION: The frequency of active HBV infection (3.8%) coupled with a high prevalence of HBV exposure in those > 50 years of age increases with age, which suggests that horizontal transmission likely relates tothe use of contaminated needles. The low prevalence of HCV infection suggests that HBV and HCV are acquired differently in this group of subjects. A: To investigate the epidemiology of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection in the two major ethnic groups in Kazakhstan. METHODS: A cross-sectional prospective study of HBV and HCV seroprevalence performed performed by individuals born in Kazakhstan with no history of chronic hepatitis or liver disease. RESULTS: There were 290 volunteers (140 Russians and 150 Kazakhs) aged 10 to 64 years, males accounted for 46%. Active HBV infection (HBsAg positive) HBP in 30%. The prevalence was similar in females and males (33% vs 25%) (P = 0.18). The prevalence of anti-HBc increased from 19% in 10-29 years old volunteers to 53% in 50-years The prevalence of HBV infection was higher in married than in single adults (38% vs 26%, respectively) (P = 0.2) and more common in Kazakhs (35%) than in Russians (24%) (P = 0.07). HCV infection was present in 9 subjects (3.2%), 5 of them also were positive for anti-HBc in the absence of HBsA g. CONCLUSION: The frequency of active HBV infection (3.8%) coupled with a high prevalence of HBV exposure in those> 50 years of age increases with age, which suggests that horizontal transmission may be tothe use of contaminated needles. The low prevalence of HCV infection suggests that HBV and HCV are acquired differently in this group of subjects.