Previous case series have reported serious complications of chicken pox (CP) after pediatric liver transplantation (PLT), mainly due to visceral dissemination. The goal of our study was to determine the incidence, risk factors, and outcomes of CP after PLT. A case-control study of all CP infections in pediatric transplant recipients followed at our center from September 1993 to April 2004 was performed. Data were collected before and after infection and at the same time points in age-, gender-, and transplant year-matched controls. Potential risk factors prior to CP and adverse outcomes after infection were compared between cases and controls. Twenty (6.2%) developed CP at a median of 1.8 yr (0.6-4.8) after PLT. All CP infections were cutaneous, with no evidence of organ involvement. Twelve were hospitalized: 9 only to receive intravenous acyclovir and 3 stayed > or =2 weeks for other complications. Risk factors were not statistically different among cases and controls. Of the outcomes analyzed, cases were significantly more likely to develop non-CP infections within one year of CP than controls (Hazard Ratio = 12.6, 95% confidence interval = 3.1-51.7; P < 0.001). These infections were often bacterial and occurred long after CP infection. In conclusion, CP is uncommon after PLT and has a low likelihood of organ dissemination. No risk factors were identified. Some cases required prolonged hospitalizations. Close monitoring for the development of late bacterial infections is warranted.