This study compared the assay results of HBV markers obtained with two automated immunoassay systems in serum samples with concomitant HBV antigens and antibodies. Eighty-nine samples of concomitant HBsAg and anti-HBs and 74 samples of concomitant HBeAg and anti-HBe were analyzed by the Abbott Architect i2000 and the Roche Elecsys 2010 immunoassay systems. The overall concordance rates of the Architect and Elecsys results were 78.6% for samples with concomitant HBsAg and anti-HBs and 77% for samples with concomitant HBeAg and anti-HBe. The data show that substantial differences exist between the results obtained by these two systems, especially in determining anti-HBs and HBeAg at low concentrations.