Summary: In order to establish a reliable method for production of antibody to bradykinin for use in radioimmunoassay, eight compounds were prepared in which bradykinin as a hapten was coupled to either a polypeptide or a protein carrier. Specific antibody was elicited by four of these compounds, as detected by binding of tritiated acetyl-N-bradykinin, and the antibody response was followed for 6 months. The various antisera obtained were compared in competition studies between unlabled bradykinin and tritiated acetyl-N-bradykinin or [14C]-2,3-proline-bradykinin. Binding affinities and antibody titers of the sera were determined from binding curves with the [14C]-bradykinin. Coupling of bradykinin to ovalbumin via toluene diisocyanate results in an immunogen which reliably elicits specific antibradykinin antibody of specificity and affinity appropriate for use in radioimmunoassay.