A patient is described in whomSalmonella schwarzengrundbacteremia was associated with infection of the aorta in the area at which a Hufnagel valve had been implanted 4 years earlier. Despite prolonged and repeated therapy with antimicrobial agents to which the organism was sensitive, an abscess developed in the aortic wall and led to a dissecting aneurysm and death.The role of the Hufnagel valve in altering the anatomy and hemodynamics in the lower aorta and predisposing to local and persistent infection is discussed. It is suggested, on the basis of the course of this patient's illness, that the appearance of bacteremia is especially ominous when such a prosthesis is present, and that antimicrobial therapy should be initiated as early as possible, that the doses used be large, and that the treatment be prolonged, without interruption. If manifestations consistent with aortic tear appear, despite apparent control of the infection, the presence of an abscess in the aortic wall must be suspected and the possibility of removal of the prosthesis and excision of the infected area be given serious consideration.