32P-HBV-DNA was used as a probe to determine HBV-DNA by molecular hybridization in the sera of 186 chronic asymptomatic HBsAg carriers (ASC). The result of HBV-DNA determination correlated closely with that of the HBeAg/anti-HBe system.The viral DNA was detected in 51(82.2%)of 62 HBeAg (+) cases but only in 1 of 103 anti-HBe ( + ) cases. The prevalence of HBV-DNA was directly proportional to the P/N ratio of RIA for HBeAg. When the P/N was above 8.1. its detection rate was 95.0%; when P/N below 5.0. it was only 12.5%. HBV-DNA determined by molecular hybridization was deemed to be a more direct proof of viral replication in ASC.