Bradykinin (BK) is an important mediator of hyperalgesia, inflammatory diseases, asthma and cancer. It is a pro-inflammatory polypeptide that can cause pain, inflammation, increased vascular permeability, vasodilation, contraction of various smooth muscles and cell proliferation by stimulating B(1)and B(2)receptors. B(1) receptors are formed in vitro during trauma, inflammatory reactions and injury. B(2) receptors are most commonly distributed in the vascular and non-vascular smooth muscle, and in the heart. Numerous BK antagonists have been developed in recent years with the prime aim of treating diseases resulting from excessive BK formation. Non-peptide B(2) receptor antagonists are now being synthesized and are under intense experimental investigation at various research centers. The most clinically useful peptide and non-peptide BK antagonists must be stable against all BK-inactivating enzymes, orally active, and have a long half-life with minimal side effects. These BK receptor antagonists may have future novel therapeutic applications in various pathological conditions associated with the abnormal kinin system.