Hepatitis B virus (HBV) and hepatitis C virus (HCV) are major causes of transfusion-transmitted infection (TTI). In Thailand, the prevalence of HBV infection in new blood donors has decreased gradually from 7.1% in 1988 to 2.6% in 2009. This drastic decline in HBV prevalence is mostly the result of an effective expanded program on immunization (EPI) against HBV; the current coverage rate with HBV vaccine in newborns is more than 98% nation-wide. The prevalence of HCV infection, has decreased at a slower rate due to lack of HCV vaccination. The use of healthy volunteer blood donors and nucleic acid amplification technology (NAT) has also contributed to the steady decrease in rates of HBV and HCV infections. We summarize the current status of the EPI program for preventing HBV and the current strategy of HBV and HCV screening in new blood donors.