Objective To study the biological effects of phenytoin（PHT） on cultured human periodontal ligament fibroblasts（hPDLF）, and explore the possibility of its accelerating periodontal regeneration. Methods Increasing concentrations of PHT （1, 5, 20, 100, 500, 2 500 mg/L） were added into the medium of the fourth passage of cultured hPDLF, respectively. After co- incubated for 3 days, cell proliferation activity, the total amount of protein and alkaline phosphatase（ALP） activity were detected. Mineralized sodium and PHT（20, 100, 500 mg/L）were added into the medium of the fourth passage hPDLF. After co- incubated, the mineralized nodules formation were detected by Von Kossa staining. The third passage hPDLF were stimulated by PHT（20, 100 mg/L）, bone morphogenetic protein- 2（BMP- 2）concentration was analyzed by enzyme linked immunosorbent sandwich assay（ELISA）. Results At the concentration of 20 or 100 mg/L, PHT significantly enhanced the proliferating activity and ALP activity of hPDLF （P
