The aim of this study was to establish the performance characteristics of a nonradioisotopic branched DNA (bDNA) signal amplification assay for quantitation of hepatitis B virus (HBV) DNA in human serum. Quantitation was determined from a standard curve and expressed as HBV DNA equivalents/mL (Eq/mL; 285,000 Eq = 1 pg of double stranded HBV DNA). The bDNA assay exhibited a nearly four log dynamic range of quantitation and an analytical detection limit of approximately 100,000 Eq/mL. To ensure a specificity of 99.7%, the quantitation limit was set at 700,000 Eq/mL. The interassay percent coefficient of variance for quantification values ranged from 10% to 15% when performed by novice users with different sets of reagents. Using the bDNA assay, HBV DNA was detected in 94% to 100% of hepatitis B e antigen-positive specimens and 27% to 31% of hepatitis B e antigen-negative specimens from chronic HBV-infected patients. The bDNA assay may be useful as a prognostic and therapy monitoring tool for the management of HBV-infected patients undergoing antiviral treatment.