We investigated the incidence of HBsAg carriers among blood donors from 107 Italian blood banks during 1986. The overall prevalence of HBsAg carriers was 1.98%. This percentage was higher in Southern (2.69%) than in Northern (1.78%) or Central Italy (0.83%). Notable differences were found in the various regions and in single centres belonging to the same region. In some small areas a prevalence of carriers as high as 10% was recorded. Most carriers had normal aminotransferase values, HBeAg was detected in 8.8% of the carriers and anti-delta in 2.9% of them. The figures from this study still suggest a persistence of an intermediate endemicity level of HBV infection in Italy, with some hyperendemic niches.