By radioimmunologic techniques, it has been possible to detect two serologically distinct elastin antibody fractions in antiserum prepared against bovine ligamentum nuchae elastin; a species specific fraction which bound only bovine elastin, and a population of antibodies with affinity for elastin from porcine aorta, bovine ligamentum nuchae and aorta, rabbit and hamster lung, and human aorta. Bovine specific antibodies were detected when bovine αelastin was used as specific ligand whereas interspecies reactivity was detected when radiolabeled nonbovine solubilized elastins were used in the assay. Two distinct antibody populations were confirmed using immunoabsorption techniques. Thus, the elastin radioimmunoassay can be modified to detect bovine or other elastins depending upon the choice of radiolabeled antigen. The assay permits determination and quantification of elastin synthesis and degradation in a wide range of species without having to raise specific antibodies to each.