Abstract: The invention relates to a highly active, highly specific urokinase inhibitor which is suitable for therapeutic applications and can be synthesized in an extremely simple manner. Surprisingly, it was found that amidino benzylamine derivatives, especially 4-amidino-benzylamine, with two bonded amino acids represent a new group of highly active and very selective uPA inhibitors. The urokinase inhibitors can be used in medical applications, e.g. in the treatment of malign tumors such as in cases of metastatic spread.