To explore the clinical efficacy of Danshen Tablet on oral leukoplakia (OLK) and its effects on the expression of metal matrix protease-2,9 (MMP-2 and MMP-9) in local tissues.Methods:A total of 136 patients with OLK treated in Nanjing Integrated Traditional Chinese and Western Medicine Hospital Affiliated to Nanjing University of Traditional Chinese Medicine from May 2014 to March 2016 were selected and randomly divided into control group and observation group,with 68 cases in each group,and 20 cases of healthy people were chosen in the same period as healthy control group.The patients in the control group were treated with retinoic acid and watermelon frost spray,and the observation group was treated with Danshen Tablet on the basis of the same treatment.Both groups were treated for 1 course (2 months as a course) and followed up for 12 months after treatment.The clinical effects of the 2 groups were compared and the expressions of MMP-2 and MMP-9 in local mucosa of OLK patients and healthy controls were detected by immunohistochemistry.Results:After 2 months treatment,the total effective rate of the observation group was 80.88%,which was significantly higher than 63.24% of the control group (P<0.05).After 4 months' treatment,compared with 2 months treatment,the total effective rate in the observation group was significantly increased which was higher than the control group (P<0.05).Compared with the healthy control group,the positive expression rates of MMP-2 and MMP-9 in the local mucosa tissues of OLK patients were significantly increased (P<0.01),and the positive expression rates of MMP-2 and MMP-9 in the local mucosa tissues in the observation group decreased more significantly after 2 months and 4 months treatment than before treatment (P<0.05 or P<0.01).The positive expression rate of MMP-2 in the local mucosa tissues of observation group was decreased more than control group (P<0.05),and the positive expression rate of MMP-2 in local mucosa tissues of the control group 4 months after treatment decreased more significantly than that before treatment (P<0.05).The recurrence rate of the observation group decreased more significantly than that of the control group during the follow-up period (P<0.05),and there was no significant difference in cancer rate between the 2 groups (P>0.05).Conclusion:The combination of Danshen Tablets and conventional drugs have significant effects on OLK.It can significantly inhibit the expression of MMP-2 and MMP-9 in local tissues,which has a positive effect on the inhibition of tissue cancer in the short term.