Posttransplantation lymphoproliferative disorder (PTLD) is a well-described complication of the systemic immunosuppression required for successful organ transplantation. Lesions of PTLD often occur in the region of the head and neck and require otolaryngologic evaluations. Although the majority of reported cases of PTLD are associated with cyclosporine immunosuppression, recently, PTLD has been described in patients treated solely with the newer systemic immunosuppressive agent tacrolimus (FK 506). As an introduction to tacrolimus and to PTLD as one of its complications, a case of PTLD presenting as airway obstruction in a child treated solely with tacrolimus immunosuppression is described. In addition, a review of tacrolimus and PTLD in patients under tacrolimus immunosuppression is presented to familiarize the otolaryngologist with this important new immunosuppressive agent and a potential complication of its use.