Posttransplant lymphoproliferative disease was first reported in 1968. Posttransplant lymphoproliferative disease encompasses a spectrum of abnormalities ranging from a benign infectious mononucleosislike illness to non-Hodgkin’s lymphoma with nodal and extranodal site involvement. In this study, we evaluated 5 children who had posttransplant lymphoproliferative disease after liver transplant. Since 2001, we have done 111 liver transplants in 108 children at our center. Five children (4.6%; 3 female, 2 male; mean age, 3.9 years) developed posttransplant lymphoproliferative disease. The indications for liver transplant were hepatoblastoma in 1 recipient and cholestatic liver disease in the remaining 4. Posttransplant lympho­proliferative disease was diagnosed 6, 11, 17, 22, and 27 months after liver transplant. Imaging modalities identified generalized lymphadenopathy in 1, multiple liver masses in 1, a large portal mass in 1, multiple stomach ulcers in 1, and a large mediastinal mass in 1 recipient. At the time of diagnosis, 1 recipient with a large mediastinal mass had a cough; the remaining 4 recipients were asymptomatic. Histologic findings showed B-cell lymphoma in 3 recipients and T-cell lymphoma in 2. The result of in situ hybridization for Epstein-Barr virus was negative in 1 recipient and it was positive in 4. Four recipients were treated with chemotherapy; the remaining recipient was treated with anti-CD20 monoclonal antibodies (Rituximab). One recipient who had a large mediastinal mass died 2 months after diagnosis due to chemotherapy-related sepsis; the remaining 4 children are alive at the time of this writing at 9, 11, 18, and 34 months after treatment. Our rate of posttransplant lymphoproliferative disease is similar to that published in the literature. From a few months to several years after liver transplant, radiologists must be alert to the possibility of posttransplant lymphoproliferative disease. Thorough imaging is required to detect the wide variety of potential presentations.