Abstract: OBJECTIVE To observe the clinical effect of ornidazole on treatment of elderly patients with periodontal purulent infections so as to provide scientific basis for clinical treatment of the elderly patients with periodontal purulent infections. METHODS A total of 94 elderly patients with periodontal purulent infections who were treated in Hainan Nongken Hospital in Hainan from Jan 2011 to Jan 2014 were enrolled in the study and divided into the observation group and the control group, with 47 cases in each group. The control group was treated with oral administration of metronidazole, while the observation group was treated with oral administration of ornidazole. The effective rate of treatment, bacterial clearance rate, clinical symptoms, and incidence of complications were observed and compared between the two groups of patients, and the statistical analysis was performed with the use of SPSS16.0 software. RESULTS The effective rate of treatment was 95.7% (45 cases ) in the observation group, 74.5% (35 cases ) in the control group, and there was significant difference in the total effective rate (%) of treatment between the two groups (t=5.312,P＜0.05). The bacterial clearance rate was 93.6% in the observation group, 68.1% in the control group, and there was significant difference (t=5.687,P＜0.05). The incidence rate of complications was 6.4% in the observation group, 10.6% in the control group, and there was no significant difference. The gingival index of the observation group was (2.16±0.51)points before the treatment, the control group(2.21±0.56)points; the gingival index of the observation group was(1.49±0.45)points after the treatment, the control group (1.72±0.56)points, and there was significant difference(t=5.104,P＜0.05). CONCLUSION Ornidazole can achieve significant clinical effect on treatment of the elderly patients with periodontal purulent infections and remarkably improve the clinical symptoms of the patients, with the safety high, and it is worthy to be promoted in the hospital.