The hemostatic properties of the pedicled omentoplasty turned out to be helpful in difficult hemorrhages in extensive surgery. As suggested by others, a high concentration of tissue factor (TF) in the omentum could be responsible for this favourable property. The authors investigated the nature of that property in 11 patients who underwent laparotomy. In omentum and striated muscle (controls) the TF-concentrations in both tissues were estimated by the ELISA method. A significant difference between TF-concentration in omentum and striated muscle could be demonstrated.