We evaluated the clinical and epidemiological data of 142 HBsAg carriers. This prospective trial is part of a program of study and follow-up in HVB patients. The median age was 34.58 years old, males 56.3%. The average follow-up was 32.4 months. Complete clinical history, routine analysis, liver function tests, alfa-fetoprotein, serology for HVB, HCV and HDV and abdominal ecography were done in all patients. DNA-HVB was done only in special cases. Patients with less than 6 months of follow-up were excluded. The 118 remaining carriers were classified into two groups, depending on ALT values. Group 1 (normal ALT): included 98 carriers, 3 of them developed an active chronic hepatitis that was treated with interferon. A small CHC was diagnosed in another patient and it was resected. Group 2 (elevated ALT): included 20 carriers, only 9 of them agreed to biopsy and we found severe hepatic lesions in 4 of them. No group presented coinfection with HCV or HDV. No patient died. We conclude that the study and follow-up of asymptomatic HBsAg carriers permits an early diagnosis and treatment of the complications of this pathology (chronic hepatitis, CHC, etc); in our study, three patients developed chronic hepatitis, successfully treated with interferon, and one small size CHC was diagnosed in another patient. The study of relatives permits also detect subclinic liver disease and facilitates vaccination to prevention transmission of this infection.