Background Hepatitis E virus (HEV) infection has been found to cause chronic hepatitis in HIV-infected patients. In Australia, where HEV is nonendemic, background seroprevalence is reportedly low but has not been evaluated in the HIV-infected population. The study aimed to assess the seroprevalence of HEV in a cohort of HIV-infected patients with normal liver function and in another group with biochemical hepatitis. Methods: Patients were selected from the Victorian HIV Blood and Tissue Storage Bank and stored plasma was tested. Positive HEV antibody specimens were examined for HEV RNA by polymerase chain reaction. Results: A total of 191 HIV patients were tested for HEV by serology. Eight of 100 (8 ) HIV-infected patients with normal liver function and 4 of 91 (4.4 ) of those with biochemical hepatitis had HEV antibodies. All four patients with abnormal liver function and positive HEV serology were coinfected with hepatitis C and were significantly more likely to have higher median alanine aminotransferase levels (382 vs 139UL-1, P=0.01). HEV-positive patients with normal liver function were more likely to be born outside Australia (P=0.004). Two of four patients with biochemical hepatitis who were seropositive for HEV had detectable HEV RNA. Conclusions: The seroprevalence of HEV in this Australian HIV-infected cohort is higher than the estimated background prevalence in the HIV-negative population. In patients coinfected with hepatitis C, the degree of alanine aminotransferase elevation was significantly worse. HEV may contribute to the development of abnormal liver function.