Background/Aims: The DD genotype of the ACE (angiotensin-converting enzyme) gene I/D polymorphism was found to be more frequent in centenarians and it was suggested that biologic functions of ACE may influence survival by resisting neoplasia or infection. ACE has been reported to enhance endogenous antigen presentation to MHC class I-restricted cytotoxic T lymphocytes, and the polymorphism intluences ACE levels in human T lymphocytes. Hepatitis B virus (HBV) infection may progress to chronic active hepatitis and liver cirrhosis, and carriers of HBsAg have an increased risk of hepatocellular carcinoma. The purpose of this study was to investigate the association between ACE polymorphism and chronic HBV infection. Methods: A total of 670 apparently healthy Korean men who attended a priodic health examination were recruited for this study. All no signs or symptoms of acute vira] hepatitis within 6 rnonths. The ACE polymorphism was genotyped by PCR amplification of the 190 and 490 bp alleles. Serum HBsAg, anti-HBs, and anti-HBc were examined by radioimmunoassay. Results: Arnong the population, 479 subjects were anti-HBc-positive. There was a significant association between HBsAg positivity and ACE polymorphism among anti-HBc-positive subjects (Chi-Square = 6.03, p = 0.049) with an increasing tendency according to the genotypes (Mantel Haenszel Chi-Square = 5.05, p = 0.025). The odds of chronic HBsAg positivity was 2.18 (95% CI = 1.15 4.15) for individuals with the II genotype compared to those with a D allele (DD + ID). Conclusions: The results suggest that D allele of ACE polymorphism may be associated with enhanced clearance of HBsAg or recovery from chronic HBV infection. Considering immunologic functions of ACE, this might be clinical evidence that helps explain a part of the long term beneficial effect of the D allele to favor human survival and longevity. (Korean J Gastroenterol 1997;29:489-496)