AIM:To evaluate seroprevalence of hepatitis A virus (HAV) antibody and investigate demographic,clinical,and laboratory features of recent cases in Korea.METHODS:For the evaluation of hepatitis A seroprevalence,we analyzed the data from 3127 subjects including,healthcare workers and patients who visited Konkuk University Hospital,a secondary referral center,from January to October 2009.The sera with positive IgM were excluded from seroprevalence data for total HAV antibody.We retrospectively reviewed the electronic medical records of 419 patients with HAV,who were diagnosed by the presence of serum IgM antibodies against HAV.All patients presented at Konkuk University Hospital between August 2005 and September 2008.RESULTS:Among 3127 sera tested,1428 (45.7%)were positive for anti-HAV antibody.The seroprevalence was very low in teenagers or those in their twenties,increased in those in their thirties,and was > 90% in older patients.In children younger than 10 years,seroprevalence was increased again.Most patients with HAV hepatitis were in their twenties and thirties.The γ-glutamyl transpeptidase increased with age and was significantly higher in patients older than 30 years.Indicators of severity,such as decreased albumin and increased bilirubin,were also more prominent in the older age group;however,the leukocyte count was higher and the frequency of leukopenia was lower in younger patients than in older adults.CONCLUSION:There has been an apparent epidemiological shift in HAV seroprevalence and a change in the peak age of HAV hepatitis.This study could provide baseline data of recent hepatitis A in Asia. AIM: To evaluate seroprevalence of hepatitis A virus (HAV) antibody and investigate demographic, clinical, and laboratory features of recent cases in Korea. METHODS: For the evaluation of hepatitis A seroprevalence, we analyzed the data from 3127 subjects including, healthcare workers and patients who visited Konkuk University Hospital, a secondary referral center, from January to October 2009. The sera with positive IgM were excluded from seroprevalence data for total HAV antibody. We retrospectively reviewed the electronic medical records of 419 patients with HAV, who were diagnosed by the presence of serum IgM antibodies against HAV. All patients presented at Konkuk University Hospital between August 2005 and September 2008. RESULTS: Among 3127 sera tested, 1428 (45.7%) were positive for anti-HAV antibody. The seroprevalence was very low in teenagers or those in their twenties, increased in those in their thirties, and was> 90% in older patients. children younger than 10 years, seroprevalence was inc reased again. Patients with HAV hepatitis were in their twenties and thirties. γ-glutamyl transpeptidase increased with age and was significantly higher in patients older than 30 years. Indicators of severity, such as decreased albumin and increased bilirubin, were also more prominent in the older age group; however, the leukocyte count was higher and the frequency of leukopenia was lower in younger patients than older adults. CONCLUSION: There has been an apparent epidemiological shift in HAV seroprevalence and a change in the peak age of HAV hepatitis .This study could provide baseline data of recent hepatitis A in Asia.