We analyzed the binding of 125I-labelled IFN-alpha to peripheral blood mononuclear cells in 19 healthy controls, 25 asymptomatic HBV carriers (AsC), and 69 patients with HBs antigen positive chronic liver disease (CLD). Histological examination showed that of the 69 patients with CLD, 14 had chronic persistent hepatitis (CPH), 46 had chronic active hepatitis (CAH), 9 had liver cirrhosis (LC). The mean number of IFN-alpha/beta receptor sites per cell totaled 1270 +/- 340 in the healthy controls, 1440 +/- 290 in AsC, and 1600 +/- 480 in CLD (with 1770 +/- 480 in CPH, 1580 +/- 490 in CAH, and 1420 +/- 410 in LC). HBV carriers had more IFN-alpha/beta receptor sites than the healthy controls (AsC: P less than 0.1, CLD: P less than 0.01). In CLD, patients with LC tended to have fewer IFN-alpha/beta receptor sites than those with CPH or CAH. The number of IFN-alpha/beta receptor sites in CLD was correlated with the HBe antigen titer (P less than 0.01), and activity of HBV-DNA polymerase (P less than 0.05). These results were suggested that IFN-alpha/beta receptor sites was higher at the HBV carrier state, and correlated with viral replication.