Twenty patients with chronic crural ulcerations refractory to previous treatment were subjected to local treatment with a solution of ovalbumin lysozyme in normal saline (1 mg/ml). Before this treatment cultures were made from the bottom of the ulcerations determining the type of the infecting micro-organism and its sensitivity to various concentrations of lysozyme. Good (5/20) and very good (15/20) results were obtained. No local or systemic unfavourable effect of lysozyme was noted. The ulcerations were cleared quickly of pus, granulation tissue developed, the inflammatory reaction around the ulcers decreased and pains were no longer felt. The cultured bacteria were insensitive in vitro to lysozyme concentrations applied in vivo. During the treatment with lysozyme the bacterial flora remained unchanged. The beneficial effect of lysozyme on wound healing may be due to its cationic influence on the cell membranes in the epithelium and to pH change in the ulcerations.