The effect of MCCH on wound healing was studied in animals and patients. A full thickness dorsal skin defect was made in mice and standard amounts of MCCH applied immediately to the wound in half the mice. There were no significant differences in wound closure rates between control and MCCH treated mice. A standard dorsal skin incision was made in rats. In half the rats, MCCH was put into the incision just before suturing with fine stainless steel sutures. There were no statistically significant differences in breaking strengths between control and MCCH treated rats when tested on the 8th, 20th and 40th days postoperatively. Histologic examination of the wounds showed mild inflammatory reaction surrounding the MCCH-fiber fragments, but no giant cells. Small amounts of MCCH were demonstrable at 40 days. Full thickness skin burns in pigs were excised one day after burning. MCCH was applied immediately in some pigs; excess MCCH was removed by saline irrigation. Split thickness skin autografts were applied. MCCH was applied to donor sites. The "takes" of the grafts were excellent and not affected by the use of MCCH and the donor sites healed uneventfully. MCCH was used in four patients with burns, three of whom underwent early excision of full thickness skin burns and immediate autografting. The fourth underwent skin grafting to the granulating areas 3 months after injury. The MCCH was applied to some donor sites and to some areas of excision. In one patient with severe burns, wound sepsis developed equally in areas with and without MCCH and the grafts were lost. In the other three patients, there were excellent takes of the grafts at all sites. All donor sites, treated and untreated, healed normally in all patients.