THE APPARENT self-liquefaction of clotted blood and auto-digestion of necrotic tissue are age-old clinical observations. Today, the reasons for the occurrence of these phenomena are now slowly becoming clear. Recent studies indicate that clotted blood is digested by proteolytic enzymes present in the blood and that necrotic tissue is digested by enzymes produced by bacteria, leukocytes, and body tissues. This new understanding-partial though it may yet be-has led to the therapeutic application of certain enzymes directly to collections of clotted blood and to infected wounds, thus providing a new approach in the treatment of patients with inflammatory and necrotic conditions. The humoral defenses and the immunologic responses of the body, plus the use of the antibacterial drugs and one of these enzymes, are combined to promote healing.