OBJECTIVE: To evaluate sinonasal manifestations of posttransplant lymphoproliferative disorder (PTLD) in the pediatric lung transplant population. STUDY DESIGN AND METHODS: Case series of children less than 18 years presenting with PTLD after pulmonary transplantation at St Louis Children's Hospital between Jan 1, 1990 and Dec 31, 2003. RESULTS: Two hundred eighty-two lung transplants were performed in 246 children. Thirty-two cases of histopathologically confirmed PTLD were identified with 8 (25%) presenting in the head and neck. Sinonasal PTLD was the most common site of head and neck involvement (63%), with 40% of patients presenting with occult disease. All patients with sinonasal PTLD had longstanding nasal polyposis related to cystic fibrosis (P = 0.07). CONCLUSIONS: This is, to our knowledge, the first report identifying an increased frequency of sinonasal PTLD after pediatric pulmonary transplantation, particularly in children with cystic fibrosis and associated nasal polyposis. Because sinonasal PTLD may be asymptomatic, this region should receive close scrutiny on surveillance evaluations.