The existence of an increasing number of apparently healthy carriers of the HBsAg demands a specific assisting attitude which must be highly reliable without increasing health care expenses. With that purpose, 129 asymptomatic carriers without prior history of jaundice and/or alcohol abuse were studied. The following discriminant criteria were used: hepatomegaly, other physical evidence of liver disease, hypertransaminasemia, and sulfobromophthalein retention. The carrier was defined as healthy after two consecutive examinations disclosing no abnormalities at intervals of six months, which occurred in 108 patients (84 %). No patient underwent liver biopsy, but the examination was still normal after two years in all cases. The presence of one or more abnormal findings was an indication for liver biopsy in 21 patients (16 %), and the procedure was accepted by 11 (52 %). The efficiency of the selection method was evaluated according to the histologic findings. The most useful criteria were hypertransaminasemia and sulfobromophthalein retention, in this order.