Objective To evaluate the clinical outcome of periodontal initial therapy on the patients with aggressive periodontitis. Methods A total of 48 patients with aggressive periodontitis, including 20 patients with localized aggressive periodontitis （LAgP） and 28 patients with generalized aggressive periodontitis （GAgP）, were chosen for the study from the patients referred to the Department of Periodontology of the School of Stomatology of China Medical University from September 2006 to December 2008. All subjects were performed periodontal initial therapy. Probing depth（PD）, clinical attachment loss（CAL）, bleeding index（BI） and tooth mobility were recorded at baseline and 1, 3 and 6 months after initial treatment. Results At 1, 3 and 6 months after periodontal initial therapy, there were significant improvements in PD, CAL, BI and tooth mobility of patients with LAgP and GAgP than those in the baseline （P
