We evaluated the stability of hepatitis B virus (HBV) DNA in plasma samples stored at 426C for external quality assessment (EQA) panels of viral load. To assess the stability of plasma samples containing different concentrations of HBV DNA, serial dilutions of HBV-infected samples with a viral load of 6.40 log(10) IU/mL were made to yield viral loads of 5, 4, and 3 log(10) IU/ mL. These were incubated at 426C for up to 7 days and then frozen at –706C. Viral load testing for HBV DNA was performed for all samples using COBAS1 AmpliPrep/COBAS1 TaqMan1 HBV Test (v.2.0, Roche, Switzerland). Results were compared with fresh frozen plasma samples as a benchmark to establish acceptable measurements on the days following sample collection. Although the results of this study demonstrated a decrease in HBV DNA viral load ranging from 0.005 to 0.30 log(10) IU/mL after storage at 426C for up to 7 days, these values did not exceed 0.5 log(10), which is the estimated intra-assay variation for molecular tests. Thus, the insignificant decrease in viral load suggests that shipment of HBV in plasma samples at temperatures of up to 426C is permissible if they are frozen within 7 days.