Infections constitute one of the main complications in organ allografts because of the immunosuppression status of the patient due to the own disease and the reduction of the immunoresponse dealing with the immunosuppressive therapy. Moreover the bacterial, micotic and parasitic infections show a lower incidence while viral infections affect more frequently the patients. On these basis the AA, report their experience on 162 kidney allografts with particular reference to cytomegalovirus pulmonary infections observed in nine patients. Five patients died of acute respiratory insufficiency while in three cases a complete resolution of the clinical picture has been observed. Finally one case underwent the association of pulmonary infection and irreversible graft failure due to rejection. The AA. conclude that the cytomegalovirus pulmonary infection is particularly riskfull in the non immunocompetent patients and stress the potent effect of the high titer specific immunoglobulins to prevent such often lethal complication.