Objective To evaluate the significance of HCV-RNA testing of blood donors by using reverse transcriptase polymerase chain reaction (RT-PCR) analysis, and investigate HCV “window period” in blood donors.Methods Test blood donors for HCV-RNA by RT-PCR, and some positive cases were followed up. Results Among 28098 routine test negative blood donors, 77 (0.27%) were HCV-RNA positive. Eleven of the 77 HCV-RNA positive donors were followed up and 9 of them were later found to have increased ALT and/or positive anti-HCV. The interval between positive HCV-RNA test and abnormal serological tests was at least 4 weeks.Conclusion RT-PCR can identify HCV infected donors at an early stage. This test should become a routine test for blood donors to further ensure blood safety.