Human granulocytic elastases have been purified by a two-step procedure involving affinity chromatography of crude extracts of leukocytic granules on Sepha-rose-Trasylol, followed by ion-exchange chromatography on CM-cellulose to resolve the isoelastases. All of these en-zymes were found to be glycoproteins with the carbohydrate content of the majorform being composed essentially of only neutral sugars. The molecular weight of this form was found to be near 30 000 daltons with the other forms being slightly higher. Preliminary structural analyses indicate that all of the elastase isozymes have identical NH2-termi-nal sequences suggesting that the differences in mobility of