We herein report the case of a leukemia patient who developed hepatitis E seven months after undergoing a transfusion with contaminated blood products. The latency period in this case was significantly longer than that of typical hepatitis E. Recently, chronic infection with hepatitis E virus (HEV) genotype 3 has been reported in immunocompromised patients. There is a possibility that our patient was unable to eliminate the virus due to immunosuppression following chemotherapy and the administration of steroids. The prevalence of HEV in healthy Japanese individuals is relatively high and constitutes a critical source of infection via transfusion. Hepatitis E is an important post-transfusion infection, and immunocompromised patients may exhibit a long latency period before developing the disease.