Objective:To evaluate the therapeutic effect of minocycline hydrochloride on chronic periodontitis.Methods:150 teeth of 75 patients dagnosed as chronic periodontitis were divided as test group(75 teeth treated by minocycline hydrochloride) and control group(75 teeth treated by 20g/L iodoglycerin).The effect of medicines were evaluated by clinical symptom combined with gingival index and the depth of pocket which were examined before and after treatment.Results:The baseline data of two groups indicated equilibrium.The status aroud the tested teeth in test group were improved

which was better than control group after 4-week treatment.The therapeutic effect of minocycline hydrochloride was better than iodoglycerin and there was statistic difference(P<0.05).Conclusion:Minocycline hydrochloride shows significant effect on chronic periodontitis.