Post-transplant lymphoproliferative disease is a complication of bone marrow and solid organ transplantation, mostly associated with Epstein-Barr virus infection and chronic immunosuppression. Even if spontaneous resolution after cessation of immunosuppressive therapy can be observed, the prognosis of this disorder is usually poor with a low response to specific treatment. We describe a case of B-cell lymphoma of the nasopharynx occurring 6 months after double-lung transplantation. In spite of its monoclonal nature, anti-CD 20 monoclonal antibody given in the presence of reduced immunosuppression resulted in a complete response. The patient also received "consolidation" radiation therapy to prevent the recurrence. The treatment was well tolerated with minimal side effects. The patient was asymptomatic and had a well functioning graft more than 1 year after therapy.