A woman in her seventies was admitted because of general fatigue and liver dysfunction (ALT 2565 IU/l). She was diabetic and, 2 months ago, began eating kikuimo (Jerusalem artichoke) containing inulin, which is thought to decrease blood sugar level. Although tests showed no evidence of acute infection of HAV, HBV, HCV, EBV and CMV, a drug-induced lymphocyte stimulation test using kikuimo extract was positive. She was first diagnosed with drug-induced liver injury according to the Japanese diagnostic criteria for the disease. After a non-eventful recovery, her serum was found to be positive for hepatitis E-antibody and RNA (genotype 3), indicating recent, autochthonous infection of HEV. The patient might have been misdiagnosed with drug-induced liver injury unless the serum test for HEV had been performed. We believe that HEV screening is mandatory for accurate diagnosis of hepatitis E and drug-induced liver injury.