The degradation of bradykinin by a highly purified preparation of rabbit brain prolyl endopeptidase and by an apparently homogeneous preparation of a bovine pituitary cation-sensitive neutral endopeptidase was studied. Peptide fragments were separated and isolated by high performance liquid chromatography and identified by amino acid analysis. Prolyl endopeptidase rapidly cleaves bradykinin at the Pro 7-Phe 8 bond. A slower cleavage also occurs at the Pro 3-Gly 4 bond. Cation-sensitive neutral endopeptidase splits bradykinin at the Phe 5-Ser 6 bond. These enzymes may participate in the regulation of brain concentrations of bradykinin.