Varicella-zoster virus (VZV) infection is immunocompromised patients may cause life-threatening complications. Prevention measures include administration of VZV immuloglobulin, acyclovir and live attenuated varicella vaccine. After vaccination, a mild varicella-like exanthem appears in up to 5% of vaccinees. Morphologically this exanthem cannot be differentiated from wild-type (wt) varicella. The risk of virus transmission after varicella vaccination, in contrast to wt varicella, is low, even in immunocompromised patients. We report on a 2-year-old girl with relapse of cereral anaplastic ependymoma, who received one dose of varicella vaccine. Two weeks later, a maculopapular rash developed while she was an inpatient on the oncology ward. Using VZV-specific PCR and restriction fragment length polymorphism (RFLP) analysis, we were able to diagnose wt varicella infection. Thus, appropriate prevention measures (VZV immunoglobulin and acyclovir) were justified for close contacts to prevent virus transmission. No secondary cases occurred.