A clinical, biochemical, and pathological study was performed in 38 chronic HBsAg carriers. The study group is a part of 393 carriers found among 117 705 voluntary blood donors at the National Blood Bank, Hospital del Salvador, Santiago, Chile. None of the 38 carriers had a past history of illicit drug abuse, hepatitis, or work involving a high risk of hepatitis B virus infection. Ten individuals had a normal liver biopsy, 17 reactive non-specific hepatitis, one fatty changes, four chr onic persistent hepatitis, one aggressive hepatitis, two post-necrotic cirrhosis, and three alcoholic cirrhosis. There was not a close correlation between liver function test and liver histology. The most significant laboratory finding was the postivity of alpha fetoprotein in two cases. During the follow-up the two alpha fetoprotein patients presented a hepatocarcinoma 12 and 14 months after admission to the study.