AbstractThe presence of hepatitis B virus (HBV) genome in sera from 73 symptomatic and asymptomatic HBsAg carriers was studied by the polymerase chain reaction (PCR) with primers specific for the S and C regions. Pre‐S proteins of the HBV envelope were detected in serum by a specific monoclonal antibody in a double immunoradiometric assay.Out of twenty‐five symptomatic patients with chronic active hepatitis (14 with HBeAg and 11 with anti‐HBe), all were positive for HBV DNA by PCR, while 14/14 HBeAg and 2/11 (18%) of the anti‐HBe patients were positive by dot blot hybridization. All but one anti‐HBe patient (96%) carried Pre‐S1 proteins. Among the asymptomatic HBsAg carriers, HBV DNA was detected by PCR in 14/14 (100%) HBeAg positive patients and in 25/34 (73%) anti‐HBe positive patients. Pre‐S1 proteins were found, respectively, in 14/14 (100%) and 11/22 (50%) of the same cases tested in parallel. The 20 healthy blood donors devoid of HBV markers and with normal transaminases tested were found negative for HBV DNA using PCR.Out of 12 patients who recovered from acute hepatitis 6, all were found negative by PCR analysis after a mean follow up of 1 year after seroconversion to anti‐HBs. When serial samples from 2 patients (one with acute hepatitis 6, the other with chronic hepatitis 6) were tested for the presence of HBV DNA and of Pre‐S1 proteins, both markers showed parallel development.The results indicate that HBV DNA detected by PCR is associated significantly with the presence of Pre‐S1 proteins (P<0.0001) and does reflect the presence of complete virions in sera from patients negative for HBV DNA by the conventional hybridization technique. The results also suggest a slower clearance of infectious particles th