A case is reported of a duodenal perforation by a Kimray-Greenfield filter hook in a 66-year-old female patient. This device had been inserted four years before, after a pulmonary embolism. The patient presented with epigastric pain, vomiting and extracellular dehydration with renal failure. A plain abdominal film showed the filter to be tilted 15 degrees to the left, with an opening 28 mm wide. Various investigations were carried out, none of which providing a satisfactory diagnosis. Steroid treatment (1 mg.kg-1 x day-1 of prednisone) was started before admission to intensive care. Only at that time gastroduodenoscopy showed on of the filter's hooks jutting through the duodenal wall. This perforation was located in the posterior wall of the third part of the duodenum, and was associated with an ulcer of the mucosa facing this hook. The diagnosis was confirmed by an abdominal CT scan. The hook was cut and the perforation sealed off during a first laparotomy. Twenty-six days later, the patient developed intestinal obstruction due to a haematoma of the jejunal wall. She later had a cerebrovascular accident, with status epilepticus and deep coma. She died four months after her admission. The late complications of vena caval filters are discussed. The position of these devices should be regularly checked by a plain abdominal film. Abdominal CT scanning is a useful investigation for the diagnosis of intra and extravascular complications.