The wound healing process was analyzed using male ICR germ-free (Gf) mice and their conventionalized (Cvz) counterparts to determine whether intestinal flora has any influence on the wound healing of a host. A longitudinal skin incision of about 35 mm was made in the dorsum of each mouse, and six interrupted sutures with 5-0 monofilament nylon thread laid for wound closure. Mice from both groups were killed on the 3rd, 7th, and 14th postoperative days, and the tensile strength of the healing wound and hydroxyproline (HP) concentration in the biologically active zone were measured as parameters of wound healing. The daily nitrogen balance and urinary creatinine excretion were also measured for 8 days. The Cvz mice showed greater tensile strength of the wound on the 3rd and 7th postoperative days, and a higher ratio of HP concentration, being wound tissue/control tissue, than their counterparts. The Cvz mice also thrived more prominently than the Gf mice, showing a positive nitrogen balance with limited urinary creatinine excretion. These results suggest the enhancing effect of normal intestinal flora on wound healing, probably through the beneficial nutritional effects supplied by the bacteria.