Receptors for polymerized human albumin (pHSA-r) are expressed on HBsAg in larger numbers during complete viral replication. We have evaluated the usefulness of pHSA-r as a marker of high-level infection by a comparison with serum HBeAg, liver HBcAg and serum HBV-DNA. One-hundred-and-fifty-seven patients with HBsAg positive chronic liver disease were tested for HBeAg and pHSA-r titre. In 73 of them liver HBcAg was tested by immunofluorescence, while in the remaining 84 serum HBV-DNA was determined. Seventy-three subjects were HBeAg positive, 20/73 were HBcAg positive, and 60/84 had circulating HBV-DNA. The best cut-off for pHSA-r was found at 1:204,800 (sensitivity of 67.6% and specificity of 95.7% in detecting viral replication). At this cut-off the concordance rate between pHSA-r and viral replication (as assessed by HBV-DNA or liver HBcAg) was 83%, a figure similar to that of HBeAg (88%). Three HBeAg negative subjects who were actually complete replicators were identified by the pHSA-r test.