Total intraparenteral nutrition therapy using an endocaval catheter is subject to complications due to the catheter itself and to the onset of phlebothrombosis of the venous district involved. Two groups of patients suffering from abdominal surgical pathologies requiring prolonged postoperative parenteral treatment were subjected to antithrombotic prophylaxis. In the first group of 20 patients, calciheparin u.s. was used and in the second defibrotide in the doses recommended in the literature. Serial lab screening of certain clotting parameters was carried of the brachio-subclavio-caval district. In the calciheparin group, the trend of certain examinations shows, as usual, a change in parameters in agreement with the drug's anticlotting action; in the group treated with defibrotide, the haemostatic balance is respected: the angiographies never showed intimal lesion or phlebothrombosis in either group. The usefulness of correct antithrombotic prophylaxis in these patients is confirmed and it is pointed out that defibrotide is more flexible and handy and that it can be used in patients in whom calciheparin is potentially risk.