This study was designed to evaluate the expression of growth factor in periodontal tissue during the experimental movement of rat incisors by LSAB(Labelled streptavidine Biotin) immunohistochemical staining for EGF(Epidermal growth factor). 23 Sprague-Dawley rats were divided into a control group(3rats) and experimental groups(20rats), where a force(75g) from helical springs across the maxillary incisors was applied. Experimental groups were sacrificed at 12 hours, 1, 4, 7 and 14 days, after force application, respectively. And Tissue slides of control and experimental groups were studied immunohistochemically and histologically. The results were as follows : 1. In 14days after force application, periodontal fibers were strectched on the tension side, and compressed in pressure side of all experimental groups, and the arrangement of periodontal fibers was not recovered yet. 2. The degree of EGF expression in control group was strongly positive in the oral epithelium, predentin, capillaries in pulp and periodontal spaces. But osteoblasts and osteoclasts were stained mildly positive. 3. EGF expression was mild and diffuse in 12 hours, 1, 4 and 7 days of experimental groups and was not significantly different between the tension and pressure sides. 4. The degree of EGF expression in the 14-day experimental group was higher than any other group. And the tension side showed a more positive EGF expression than the pressure side. The apical area revealed a more positive EGF expression than the cervical area.