TRICOMED S.A. (Poland) has modified its own knitted polyester vascular prosthesis by change in its physical and chemical characteristics and using hydrophilia. The work has aimed at evaluation of intraoperative tightness and evaluation of change in the number of selected parameters of coagulation and fibrinolysis following implantation of a hydrophilic vascular graft into the thoracic aorta defect in piglets. In view of the experimental tests performed it has been noticed that use of DALLON H prosthesis is easy and the handling of the graft is the same as that of other knitted vascular grafts. DALLON H prosthesis does not need preclotting and it reaches immediate tightness after the blood flow has been restored. In view of the results of the blood studies after implantation coagulation activation in endogenous and exogenous system (aPTT and PT), and increase in activity of factor XII and VII. Concentration of fibrinogen was at a higher level. Thrombin III activation remained at the same level after a primary increase, but protein C activation was decreased. Plasminogen activation was higher which means that the fibrinolytic system was activated. Changes in the level of evaluated indicators were observed until day 14 after implantation of the prosthesis. On day 21st the values of the selected parameters were equal with the values prior to implantation.