Herpes simplex virus hepatitis (HSV hepatitis) is an uncommon and severe complication of HSV type 1 and HSV type 2 infection. HSV hepatitis affects mostly immunocompromised patients. We report the case of a young man without any previous known immunodeficiency who developed fatal HSV hepatitis in the first 8 days of oral corticotherapy given for ulcerative colitis. A prompt diagnosis was possible because HSV was recovered from peripheral blood leukocytes.