Two patients complained of severe abdominal pain as the first sign of varicella zoster virus infection about 1 year after allogeneic BMT. In case 1, eruptions, found on the face and chest on admission, became vesicular and dispersed on the third hospital day. Though acyclovir (ACV) was immediately started, he died on the fourth day. In case 2, skin rash was never observed during the clinical course. Laparotomy on the third hospital day revealed many hemorrhagic spots on the liver surface and mucous membrane of the upper GI tract, indicating disseminated visceral disease. Empiric therapy with ACV was successful.