Five faecal samples were collected from four different stages of production at each of 10 pig farms in the Yorkshire Humberside area of the uk, and samples of slurry were collected from nine of the farms. All the samples were tested for hepatitis E virus (hev) rna by a nested reverse transcriptase pcr. At least one sample from the pigs on each of the farms tested positive for hev; its prevalence in the 10 herds varied from 5 per cent to 35 per cent and its mean prevalence was 21·5 per cent. The mean prevalence in pigs aged three to five weeks was 26·0 per cent, in pigs aged 10 to 12 weeks 44·0 per cent, in pigs aged 22 to 24 weeks 8·9 per cent, and in adult dry sows 6·0 per cent. Two of the nine slurry lagoons tested positive for hev rna. Phylogenetic analysis of the sequence data indicated that the strains of the virus were of genotype 3 and closely related to strains detected in other pigs and in human beings in the uk.