Varicella, a contagious viral disease, is typically self-limited but can result in serious complications, especially among persons who are immunocompromised. On April 10, 2012, a girl aged 4 years with acute lymphoblastic leukemia (ALL) was exposed to a mildly ill cousin who developed a varicella rash 2 days later. The episode was reported to the child's oncologist after 13 days. The girl was prescribed 7 days of oral acyclovir for prophylaxis and concurrently began her scheduled chemotherapy, which included a 5-day course of dexamethasone (prednisone equivalent dose of 23 mg/day). Twenty-two days after her varicella exposure, the girl was taken to an emergency department for fever and abdominal pain. She was treated symptomatically; her caretakers were instructed to discontinue chemotherapy and to follow up with her oncologist. Two days later, the girl returned to the emergency department with a generalized rash. She was hospitalized and treated with intravenous acyclovir and antibiotics. However, she developed multiorgan failure and died on May 7. Varicella was confirmed by polymerase chain reaction testing, and no alternative diagnoses were found for her acute illness.