Objective : The purpose of this study is to report the effectiveness of a long-term Korean Medicine Treatment on 511 atopic dermatitis patients. Methods : Total 511 atopic dermatitis patients, who has visited oriental medical clinics from 2011.1.9 to 2012.1.31 and continued treatment 3 month to 9 month were analyzed by Objective SCORAD Index(OSI). Subanalysis of OSI were done according to gender, age, treatment period, and intensity. Results : 1. Male and female percent was 42.5:57.5. Age percent was 0 to 11:12 to 18:above 19=30:16.6:53 and 41.9% was steroid users. 2. OSI Improvement rate was significantly higher in women than men after 3 month of treatment, but not significant after 6, 9 month of treatment. 3. There was no improvement difference of OSI among the age. 4. OSI was significantly lower after 3, 6, 9 month of treatment. Average post-treatment score was lowest in 9 month treatment group. 5. 86.7% of total patients reported decrease in OSI score at the final visit. 6. 85.9% was severe, 13.5% was moderate, and 0.6% was mild by OSI intensity assessment at initial visit. The percent changed at final visit to 37% severe, 54.2% moderate, and 8.8% mild. 7. Patient diagnosed as OSI intensity severe at first visit, their average treatment period was 6.58 months and final improvement rate was 36.27%. Conclusion : A significant percent of Atopic dermatitis patients who were treated with Korean Medicine Treatment reported decrease in OSI. There was significant decrease in OSI before and after 3, 6, 9 month treatment. The difference increased with the treatment period.