In order to find a new treatment of periodontitis, this paper studied the effects of Gu Chi Gao on IL-8 in gingival crevicular fluid (GCF) of periodontitis. One tooth was selected from every patient in 24 patients with adult periodontitis. After supragingival scaling, the patients were divided into two groups randomly. One group was treated with Gu Chi Gao, while the other group was untreated as control group. All patients were examined after one month. GCF samples were collected with 2 mm x 20 mm Whatman I filter paper stripes and IL-8 in the GCF samples were detected by the method of ELISA. The result demonstrated that the levels of GCF and IL-8 in the treated group were lower than that of control group (P < 0.01), it suggests that Gu Chi Gao may inhibit the production of IL-8 and GCF.