Objective To investigate the effect of the traditional Chinese medicine Yunan Baiyao on the socket healing of impacted mandibular third molar extraction. Methods A total of 200 paticnts requiring extractions of impacted mandibular wisdom teeth were randomized into the treatment group and the control group in a double-blinded manner,and Yunan Baiyao capsules or placebo capsules (2 g/d) wereorally administered for 28 days after the operation.Dental quantitative CT scan was performed,and thevolume and density of new bone at the extraction site were measured two month after operation.Results Atotal of 188 patients completed the study.No adverse events related to the medication occurred.The volume of new bone was (477.39 ± 166.47)mm3 in the treatment group and (442.65 ± 143.58)mm3 in the control group,which was not significantly diffcrent between the two groups.The density of new bone was (296.90 ±37.94) mg/cm3 in the treatment group and (298.54 ±40.21 ) mg/cm3 in the control group,which was not significantly different between the two groups.The density of new bone was ( 296.90 + 37.94) mg/cm3 in the treatment group and (298.54 +40.21) mg/cm3 in the control group,which was not significantly different between the two groups.The number of the teeth root,the impacted conditions,whether or not retainning the alveolar septum,suturing soft tissues of the extraction site.and blood clot formation within 1 week after operation were signif'icantly correlated with the volume of new hone.Conclusions Yunnan Baiyao capsules has no effect on the volume and density of new bone at the extractionsite two months after operation following extractions of impacted mandibular third molars.