Department of Medicine, Royal Free and University College Medical School, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, UK 1 Department of Hepatitis, National Institute for the Control of Pharmaceuticals and Biological Products, Temple of Heaven, Beijing, PR China 2 Author for correspondence: Tim Harrison. Fax +44 20 7433 2852. e-mail t.harrison{at}rfc.ucl.ac.uk Isolates of hepatitis E virus (HEV) have recently been described from China that are distinct from Burmese, Mexican and US viruses and constitute a novel genotype (genotype 4). Here, the complete genomic sequence of a representative isolate of genotype 4 HEV, amplified directly from the stool of an acutely infected patient, is presented. Analysis of the entire sequence confirms our previous conclusion, based upon partial sequence data, that these Chinese isolates belong to a novel genotype. Typical of genetic variation in HEV, most nucleotide substitutions occur in the third base of the codon and do not affect the amino acid sequence. The genotype 4 virus is unusual in that a single nucleotide insertion in the ORF 3 region changes the initiation of ORF 3, and perhaps also ORF 2. The consequences of these changes are discussed.