Hepatitis A virus (HAV) is one of the most important causes of acute infectious hepatitis. The aim of this study was to determine the genotypes of HAV that have been circulating in Koreans. A total of 76 sera referred to our institute for HAV genotyping from 11 Korean provinces were used for this study. Those samples were diagnosed by positive of IgM anti-HAV. HAV RNA was extracted from 150 microliter of serum, and reverse transcription PCR-sequencing was used to detect and characterize HAV RNA. Primer pairs from the VP1/2A region of the HAV were used for amplification and sequencing. HAV RNA was found in 64.5% (n = 49) of the 76 patient sera with acute hepatitis A. Forty-seven strains were genotype IIIA in a total of 49 isolated strains (95.9%, 47/49); only two strains belonged to genotype IA (4.1%, 2/49). Thirty eight genotype IIIA isolates were 100% identical to consensus amino acid sequences of the reference strain AJ299467. The amino acid change of L772F was found in two IIIA strains; other IIIA isolates showed one amino acid change. Amino acid of genotype IA was compared to reference strain L20541. K801R was found in 1 strain and Q810S in both strains. The amino acid change of K801R was the first report in Koreans. Until recently HAV genotype IA has been reported as a major circulating HAV genotype in Koreans. In the present study, the predominant HAV strain in Koreans seemed to be HAV genotype IIIA.