Abstract: PURPOSE To detect the change of secreted frizzled-related protein-1（SFRP1） in gingival crevicular fluid during periodontal initial treatment and explore the relationship between SFRP1 and the activity of chronic periodontitis. METHODS Twenty-two patients with moderate to severe periodontitis were selected, and 5 healthy volunteers were enrolled into the study as control group. The bleeding index(BI),periodontal probing depth(PD)and clinical attachment loss(CAL) were recorded at 1 week after supragingival scaling, one month after subgingival scaling. Gingival crevicular fluid (GCF) was collected at 1 week after supragingival scaling, one week after subgingival scaling, one month after subgingival scaling. The level of SFRP1 in GCF samples was detected by ELISA. SPSS19.0 software package was used for data processing. RESULTS The amount of SFRP1 in GCF of moderate to severe periodontitis group was (40.80±4.85) pg, and that of normal control was (33.42±2.24) pg at 1 week after supragingival scaling. The amount of SFRP1 in GCF was significantly higher in moderate to severe periodontitis compared to normal control group (P<0.05). In moderate to severe periodontitis group, the amount of SFRP1 in GCF significantly increased at l week after subgingival scaling (45.99±5.23) pg compared to 1 week after supragingival scaling and 1 month after subgingival scaling (36.92±4.00) pg (P<0.05); There was significant decrease in the amount of SFRP1 in GCF at 1 month after subgingival scaling,compared to 1 week after supragingival scaling and l week after subgingival scaling (P<0.05).CONCLUSIONS The BI, PD in the periodontitis groups were significantly improved at 1 month after initial therapy,and the amount of SFRP1 in GCF changed with different periodontal inflammation state．