To the Editor.— Transvenous interruption of the inferior vena cava for prevention of recurrent pulmonary embolism by the umbrella filter of Mobbin-Uddin has been extensively used for more than a decade. Such devices may be associated with immediate or remote complications. The presence of sepsis has been considered as a contraindication to insertion of the filter. We have seen a case of septicemia from infection of a previously inserted filter. Report of a Case.— A 56-year-old man was hospitalized with a febrile illness of one week's duration. There was a recent history of blunt injury of right elbow. Two years previous the patient had sustained fracture of the left fibula. This was followed by occurrence of angiographically proved pulmonary embolism, for which he was treated with anticoagulant agents. Because there was recurrence of pulmonary embolism, a 28-mm umbrella filter was inserted into the inferior vena cava at the level of