BACKGROUND: To prevent blood-borne infections and guarantee safe transfusion, we proposed a quality assurance program for donor screening tests, such as hepatitis B surface antigen (HBsAg) and anti-hepatitis C virus antibody (anti-HCV), by introducing external proficiency testing for the laboratories that perform donor screening tests. METHODS: The materials for external proficiency testing (PT) were prepared from the HBsAg Standard Panels and anti-HCV Reference Panels provided by the Korea Food and Drug Administration (KFDA), and the normal Human Serum was provided by the Serum Bank of the Korea National Research Resource Center. The external PT materials were sent to 83 laboratories that performed donor screening tests after evaluating their quality. RESULTS: The results of evaluating the quality of the PT materials were acceptable. All the laboratories receiving the materials answered with a 100% response rate. All the laboratories answered that they obtained positive results for the HBsAg Standard Panel E, H, I and J; however, one laboratory answered in the gray-zone and that lab had negative results for HBsAg Standard Panel C and G. Seventy laboratories (84%) and 42 laboratories (51%) among the total 83 laboratories answered they had positive results for HBsAg Standard Panel B and D, suggesting that many laboratories could not detect a low level of HBsAg. All 83 laboratories answered that they had concordant results for the external PT for anti-HCV. CONCLUSION: Donor screening laboratories can detect low levels of HBsAg and anti-HCV without any errors and the performance of the laboratories that could not detect low levels of HBsAg remains to be improved. Quality assurance program using external PT with materials that contain various genotypes and mutants should be conducted to maintain the quality of donor screening tests.