OBJECTIVE To study the particle of hepatitis E virus (HEV) and its significance in specific diagnosis for hepatitis E (HE). METHODS Four strains of monoclonal antibodies (McAb) against HEV, 5B12, 5F1, 5B9 and 4G10, were prepared with HEV antigen (used as immunogen) expressed by genetic engineering and detected by indirect enzyme-linked immunosorbent assay (ELISA) with purified synthetic polypeptide antigen. RESULTS The monoclonal anti-HEV prefared could produce inhibitory reaction with anti-HEV positive serum and combined specifically with HEV particle forming virus-antibody complex seen clearly under electron microscope. CONCLUSIONS McAb against HEV so prepared with high specificity can be used to detect and identify HEV.