Zoonotic transmission of hepatitis E virus (HEV) from captured wild deer or boars to humans has been suggested. Antibody to HEV was detected in 9% of 35 wild boars and 2% of 117 wild deer tested, and a presumably indigenous HEV of genotype 3 was isolated from a boar in Japan.Hepatitis E virus (HEV), the causative agent of hepatitis E, is an important human pathogen (4,18,21). The genome of HEV is approximately 7.2 kb in size and contains three open reading frames (ORF1, ORF2, and ORF3) (18). Although only one serotype has been recognized, extensive genomic diversity has been noted among HEV isolates, and HEV sequences have tentatively been classified into four genotypes (genotypes 1 to 4) (20). Transmission of HEV occurs primarily by the fecal-oral route through contaminated water supplies in developing countries (18). In addition, increasing evidence has indicated that hepatitis E is a zoonosis (4, 8, 10-13, 15, 16, 21, 24, 29). It has recently been suggested that zoonotic foodborne transmission of HEV from domestic pigs, wild boars, or wild deer to humans plays an important role in the occurrence of cryptic hepatitis E in Japan, where people have distinctive habits of ingesting raw fish (sushi or sashimi) and, less frequently, uncooked or undercooked meat (including the liver and colon or intestine of animals) (9,23,24,29). The first animal strain of HEV to be isolated and characterized was a swine HEV from a pig in the United States in 1997 (10). Since then, many swine HEV isolates, which exhibit extensive genetic heterogeneity, have been identified worldwide and shown to be genetically closely related to strains of human HEV (1,3,5,6,16,17,(25)(26)(27)30). In previous studies, a high prevalence of the swine immunoglobulin G (IgG) class of antibody to HEV (anti-HEV) was found among 2-to 6-month-old Japanese pigs (58% or 1,448 of 2,500) (22), and a pair of Japanese swine and human HEV isolates of genotype 4 with 99% identity over the entire genome were identified (15). In addition, a certain proportion of packaged raw pig livers for sale in stores as food (1.9% or 7 of 363) were contaminated with HEV, which had high nucleotide sequence identity, up to 100%, with the HEV isolates recovered from Japanese patients with hepatitis E who had ingested undercooked pig liver before disease onset (29). As for HEV from wild boars, although Chandler et al. (1)