For over 2000 years, leeches have been placed on the human body to provide relief from various medical conditions. During the medieval ages, leeches were used in bloodletting in an attempt to restore the body’s four “humors.” Now, however, modern science has proved that the saliva from a leech bite provides a powerful anti-coagulant agent useful in the treatment of hypertension, as well as a host of other cardiovascular ailments. Because leech saliva contains the enzyme Hirudin capable of producing these anti-clotting properties, and there is a significant loss of blood during the therapy, “hypovolemic hemodilution” may occur, which directly lessens the pressure along blood vessel walls. This, in turn, may reduce the overall blood pressure of the hypertensive patient.