Abstract: Objective To assess the efficacy and safety of combined ⁹⁹Tc-methylenediphosphonate(⁹⁹Tc-MDP)and lower-dose methylprednisolone in the treatment of old patients with active moderate-to-severe Graves ophthalmopathy.Methods Twenty-four old patients with active moderate-to-severe Graves ophthalmopathy were randomly divided into two groups,that were methylprednisolone group(control group)and combination of ⁹⁹Tc-MDP and methylprednisolone group(experimental group).The two groups were similar in age,sex,duration and severity of ophthahnopathy.Patients in control group were treated with intravenous high-dose methylprednisolone pulse therapy(cumulative dose of 800~1200 mg).experimental group were treated with combination therapy of ⁹⁹Tc-MDP and lower-dose methylprednisolone(cumulative dose of 300~480 mg).At 12-week follow-up,therapeutic outcome was assessed by the change in clinical activity score and severity classified using Americom Thyroid Association of thyroid-associated ophthalmopathy indexing classification stcmdard.The adverse effects were observed and recorded in all patients.Results The remarkably effective outcome was observed in 6/12(50.0%)cases in control group and 10/12(83.3%)cases in experimental group.There were significant differences in the degree of improvements in ocular involvements.Less frequent and severe adverse effects were observed with the addition of ⁹⁹Tc-MDP to lower-dose methylprednisolone therapy.Conclusion A combination of ⁹⁹Tc-MDP and lower-dose methylprednisolone may be better tolerated and more effective than high-dose ophthalmopathy.