Abstract: An affinity chromatography method for the separation and pruification of two active forms of urokinase from a crude urokinase preparation. The method employs an extracting agent of agmatine covalently coupled to the surface of a water-insoluble solid support material such as agarose, and three separate specific buffer solutions. A low ionic strength buffer, such as 0.01 molar sodium phosphate buffer, pH 6.0-9.0, is used in preparing the loading solution and for washing the extracting agent. A slightly higher ionic strength buffer, such as 0.02 molar sodium phosphate buffer, pH 6.0-9.0, is used as a first eluant for eluting from the extracting agent a first active form of urokinase which is characterized by a molecular weight of approximately 33,400 and a specific activity of approximately 226,000 CTA units/mg protein. A still higher ionic strength buffer with added salt, such as 0.1 molar sodium phosphate -- 0.4 molar sodium chloride buffer, pH 5.0-8.