B AC K G R O U N D We evaluated the distribution in society of antibody seroprevalence against HAV according to age group and the change in seroprevalence levels over a 10-year period. M ET H O D S Totally, 1.271 cases were enr o lled and 812 of those in first per iod, and 459 in the second. Anti-HAV IgG ser op os it ivity in all cases decr e ased to 78.4% from 86.6%. R E S U LT S When seropositivity levels were compared between two periods, this reduction in the second period was regarded as statistically significant (p=0.0003). On the other hand, the seropositivity of that had declined from 32.4% to around 29% in the ≤15 age group (p=0.83), and from 94.8% to 84% in the >15 age group (p=0) over the 10- year period. CO N C L U S I O N S Our results could be rel ated to dev el o pment of soc ioec on omic cond it ions, more strictly controls of water and food sou rces, and educ at ion of peo pl e .