A multivalent Kunitz-type serine protease inhibitor derived from human urine, with potential protective, anti-fibrinolytic and anticoagulant activities. Upon administration, ulinastatin (or urinary trypsinogen inhibitor) inhibits the activities of a variety of enzymes, including trypsin, chymotrypsin, thrombin, kallikrein, plasmin, elastase, cathepsin, lipase, hyaluronidase, factors IXa, Xa, XIa, and XlIa, and polymorphonuclear leukocyte elastase. In addition, ulinastatin inhibits the excessive release of proinflammatory mediators, such as tumor necrosis factor-alpha, interleukin-6 and -8, and chemokines. Altogether, this agent may improve the microcirculation, perfusion and function of tissues and may protect organ injury.