LEDs have been shown to be a safe, efficient, light-weight, and less-expensive alternative to heal wound. LED irradiation at the same biostimulatory wavelength of previous laser studies have similar biochemical effects The purpose of present study is to evaluate the effects of wound healing by LED irradiation. Thirty 34-day-old sprague dawley were used for present study. 1.5mm diameter defected holes were formed in both ear lobes of rat by rubber dam punch. 635nm and 890nm irradiation was performed by LED for 2 weeks, followed by histologíc examination staíned with H&E and Masson trichrome. Also, RT-PCR was carried out to find out the mRNA expression level in gingival fjbroblast irradiated by 635nm for 1 hour. In gross exarnination, wound healing was observed in irradiated group comparing to control For microscopic exarnination, repair by connective tissues was filled in defects of irradiated group, while dense cellular bands consisting of fjbroblasts and capi llaries were found at the end of defect in control By staining of masson trichrome, amount of collagens were found in irradiated group. In a result of RT-PCR, mRNA expressions of TGF- ß , MMP-1,3 and Timp-3 were down-regulated in irradiated group comparing with their expression in control group. Taken together, LED irradiation increase the prolifeation and the activity of fibroblasts and down-regualted the TGF-ß , MMP- 1,3 and Timp- 3 mRNA, followed by activation of would healing.