Abstract: In order to determine whether fluoride would induce apoptotic cell death, our research group monitored DNA fragmentation and the cellular morphology with Hoechst33342/PI double staining，DNA ladder and transmission electron microscope (TEM). The level of apoptosis was analyzed with a fluorescenceactivated cell sorter (FACS) by the Annexin-V-FITC and the propidium iodine (PI) double staining method. Cell-cycle analysis was also examined with FACS using PI staining. The experimental results were as follows:Ultrastructural features of osteoblasts in control group exhibited clear nuclear envelope,large nucleolus, even karyoplasms, abundant endoplasmic reticulum and mitochondria. When fluoride was more than 1.0×10－4 mol/L, cellular membrane disintegration, cytoplasm condensation, chromatin compaction or fragmentation, endoplasmic reticulum (ER) expansion, nucleus shrinkage or periphery were observed Fluoride at 1.0×10^－5-2.5×10^－3 mol/L induced apoptosis with DNA fragmentation. FACS cell-cycle analysis demonstrated that fluoride caused potent G0/G1 arrest. Few cells could be found either in the S phases or the G2/M, thus inhibiting the transformation from S phase into G2/M phase under high levels of fluoride. The highest apoptosis rate of earlier and later stages were induced by 1.0×10^-4 mol/L fluoride(3.33% and 2.92% respectively).In conclusion, the results revealed that fluoride can induce apoptosis in osteoblast.