We report the case of a 37-year-old man who underwent bilateral lung transplantation for end-stage cystic fibrosis. Two months after his operation, a computed tomographic scan showed multifocal nodules throughout both lungs. Endobronchial biopsies revealed an Epstein-Barr virus-associated B-cell lymphoproliferation. Transbronchial biopsies revealed perivascular lymphoid infiltrates composed of predominantly small T lymphocytes. These perivascular infiltrates were retrospectively considered to be an acute cellular rejection rather than the periphery of the lymphoproliferative disorder. This opinion was based on several arguments: (a) a decrease in dosage of maintenance immunosuppression led to total regression of the lymphoproliferation but did not affect the perivascular lymphoid infiltrates; (b) the treatment of the acute cellular rejection temporarily induced the disappearance of the perivascular infiltrates; (c) the expression of Epstein-Barr virus was not detected in the perivascular infiltrates; and (d) on autopsy, performed 1 year later, severe obliterative bronchiolitis lesions were discovered, for which acute cellular rejection is the main risk factor. These observations point to the possibility that acute cellular rejection and an Epstein-Barr virus-associated lymphoproliferative disorder may coexist.