To evaluate the current status of hepatitis A virus (HAV) infection, a seroepidemiologic study to detect the prevalence of antibodies against HAV (anti-HAV) has conducted in Taipei City, from March to July, 1989. Serum specimens were collected from 602 male and 503 female apparently healthy children age 12 and under. The prevalence rate of anti-HAV was 27.5% in infants, and decreased to nearly 0% in preschool and early school children up to 10 years old. Compared to a previous study in the same area of Taipei in 1984, our study indicated a further and significant reduction in the prevalence of anti-HAV in almost every age group from 2 to 14 years of age. There was an average of a 5-year prevalence shift. These data suggest that there has been no significant endemic of HAV infection from 1984 to 1989. The antibody prevalence change in the different age groups represents an ongoing trend of HAV seroepidemiology in Taiwan where HAV infection is becoming rare. The age of primary infection in children has been extended to an older age group. The rarity of HAV infection in Taiwan has created a large and growing population of young adults susceptible to hepatitis A virus infection. The effective prevention of hepatitis A virus infection will become a major public health concern.