We describe a patient with acute lymphocytic leukemia (ALL) who developed visceral varicella-zoster virus (VZV) infection following cord blood stem cell transplantation (CBSCT) and was successfully treated with intravenous acyclovir (ACV). A 24-year-old woman with ALL developed severe epigastric pain 168 days after CBSCT, followed by blistering eruptions 2 days later. A diagnosis of visceral varicella-zoster disease was made, and early intravenous ACV therapy successfully alleviated the epigastric pain and skin lesions within 2 weeks. Polymerase chain reaction analysis of the serum showed dramatic decreases in the viral DNA copy number and revealed large viral concentrations prior to the skin manifestations. The viral DNA copy number in whole blood remained positive, however, but was reduced. Further treatment with intravenous ACV led to VZV DNA becoming undetectable in whole blood, a result not achieved with oral valacyclovir.