Abstract: PURPOSE To study the impact of smoking on human beta defensin 2,3 expression in gingival crevicular fluid and gingival tissue of patients with chronic periodontitis. METHODS The study subjects were divided into chronic periodontitis with smoking and without smoking. Enzyme linked immunosorbent assay (ELISA) was used to detect the concentration of hBD2,3. RT-PCR was used to detect the mRNA expression of hBD2,3. SPSS17.0 software package was used for statistical analysis. RESULTS In GCF, the expression level of hBD2,3 in the smoking group was significantly lower than that in the non-smoking group. The mRNA expression level of hBD2,3 in the smoking group was weakened compared with that in the non-smoking group.CONCLUSIONS Smoking can change the expression of hBD2,3 in both GCF and gingivae, which indicates that smoking may have a negative effect on the immune defense system of the periodontal host.