A total of 1,741 asymptomatic hepatitis B surface antigen (HBsAg) carriers in two areas (Okinawa and Kyushu) in Japan were surveyed for the presence of hepatitis B e antigen (HBeAg) and the corresponding antibody (anti-HBe) to determine the age-specific prevalence of these markers and the mean age of carriers with HBeAg. Prevalence of HBeAg was significantly higher in Kyushu (36.4% of 755 carriers) than in Okinawa (20.0% of 986 carriers) (P less than 0.001). The mean age of carriers with HBeAg was 25.5 years in Kyushu and 16.1 years in Okinawa, suggesting that HBeAg converted to anti-HBe earlier in Okinawa than in Kyushu. In contrast, the prevalence of anti-HBe was significantly higher in Okinawa (74.6% of 986) than in Kyushu (56.3% of 755) (P less than 0.001). The prevalence of HBeAg decreased with age up to 40-49 years of age and then increased in both areas. Prevalence of anti-HBe was inversely related to the prevalence of HBeAg in both areas. These data suggest that HBeAg and anti-HBe are chronological markers of chronic hepatitis B virus infection and that the duration of HBeAg persistence can be different in different area, even in the same country.