BACKGROUND AND AIMS: The etiology of acute viral hepatitis in Korea has been dynamically changing during the recent years. The aim of this study was to investigate the recent etiology and the clinical features of acute viral hepatitis in a single center of Korea. METHODS: We performed a retrospective analysis of a prospective cohort of 55 patients who were diagnosed with acute viral hepatitis A to E during the period from May 2005 to August 2006. In addition to the clinically acute manifestations, the confirmatory serological tests were performed for the diagnosis of acute hepatitis A, B, C and E. RESULTS: The proportion of patients with acute viral hepatitis A, B, C, E and others were 56.4% (n=31), 12.7% (n=7), 18.2% (n=10), 9.1% (n=5) and 3.6% (n=2), respectively. The mean age of the patients with acute hepatitis A, B, C and E were 29.1+/-4.38, 38.7+/-11.72, 45.3+/-17.62 and 32.4+/-6.58 years, respectively. There was no fatal case. All cases of acute hepatitis B and six out of ten cases of acute hepatitis C recovered spontaneously. Four out of the five patients with acute hepatitis E had no history of travel to endemic area. CONCLUSIONS: The most common etiology of acute viral hepatitis in Korea is hepatitis A virus, and hepatitis C and B virus were the next most common causes. The sporadic cases of acute hepatitis E were not rare, and coinfection of HAV and HEV was observed. A multicenter, prospective study is warranted in the future.