We determined the presence of anti-HEV IgM antibody, anti-HEV IgA antibody, and HEV RNA in serum samples of 73 notified cases that were recorded on the day of disease onset. HEV RNA was detectable until 3 weeks after disease onset. Both IgM and IgA anti-HEV antibodies were positive until 40 days after the disease onset. Among the HEV RNA positive patients, 41 out of 60 symptomatic and 2 out of 54 asymptomatic ones had genotype 4 HEV, respectively. Only 23.3% (14/60) of HEV RNA positive patients in the asymptomatic group were confirmed the presence of anti-HEV antibodies. Testing for the presence of both anti-HEV antibodies and HEV RNA would be beneficial for the comprehensive diagnosis of hepatitis E infections.