The purpose of this study was to evaluate the effect of dexamethasone on the healing aspect of gingiva and alveolar bone after extraction. Extracted socket of 24 Sprague-Dawley rat was used. To extract easily and minimize injury, ${eta}-APN$ 0.2g/kg/day soluted in mineral water was administrated for 5 days before extraction in both group. Ampicillin 1.5ml/kg i.m.,q.d, was administered for preventing infection after teeth extraction in both group, and dexamethasone 0.2mg/kg/day was injected for 3 days in experimental group.3 rats on each day was sacrificed on 1, 3, 7, 15 days after extraction. Histologic examination and the activity of osteoclasts by tartrate resistant acid phosphatase was observed. The results were as follows : 1. The Overall healing pattern was similar with both the experimental and control group, but in experimental group osseous healing was delayed. 2. The activity of osteoclasts was increased to day 3 and then decreased after day 3 in the experimental group. In comparison to the control group, the experimental group showed increased appearance to day 7 and then decreased appearance following day. 3. Regarding to the change of osseous tissue, the activity of osteoblasts was shown at day 7,but osteoclastic activity of the experimental group was less than that of the control group. The osteoclastic activity was statistically significant between two groups except day 7(p<0.05, p<0.01). In conclusion, the effects of dexamethasone for healing of extraction socket were considered as limiting the activity of osteoclasts, and the healing of extraction socket was delayed.