In HBsAg carriers, the HBeAg has been regarded as an effectively infectious and progressive factor to B viral hepatitis. On the basis of the author's actual observations, it is clear that the clinical and pathological significance of HBeAg must be carefully reviewed. In the process, the problems to be focused upon are: 1) natural history of HBeAg and anti-HBe, 2) the clinical course before and after seroconversion from HBeAg to anti-HBe, and 3) the correlation between prognosis of B viral hepatitis and persistence of HBe-Ag and anti-HBe. On the basis of the author's observations, the author wishes to stress that to date we have only been able to observe an aspect of natural history of HBeAg and anti-HBe, and that the clinical and pathophysiological significance of HBeAg and anti-HBe remain still unexplained.