The invention relates to a natural or synthetically producible protein which acts as a clotting inhibitor and can be isolated from the saliva of insects which suck mammals' blood. The preferred insect in Triatoma pallidipennis. The protein is used in the treatment of thrombosis or unstable angina or arteriosclerosis or to prevent vessels from reclosing after PTCA/PTA or to prevent blood from coagulating in haemodialysis.
