ObjectiveTo observe the efficacy of technetium-99 methylenediphosphonate (99Tc-MDP) combined with methylprednisolone sodium succinate (MSS) on thyroid-associated ophthalmopathy (TAO). MethodsTotally 42 TAO patients with a disease course less than 1 years were randomly divided into two groups: the experimental group was treated with 99Tc-MDP combined with MSS (40 mg/d for one month) and the control group was treated with MSS alone (40 mg/d for four months). The degree of exophthalmos and TAO activity were observed before and after treatment and were compared between the two groups. ResultsThe clinical symptoms of TAO were improved in both groups. The effective rate for exophthalmos degree was 90.9%(20/22) in the experimental group and 65%(13/20) in the control group, and there was significant difference between the two groups ( P<0.05 ). The clinical efficacies for TAO ophthalmopathy activity were not significantly different between the two groups (P>0.05 ). No 99Tc-MDP-associated adverse reactions were found in the experimental group. Conclusion99Tc-MDP combined with MSS shows satisfactory effect for treatment of thyroid-associated ophthalmopathy, especially for exophthalmia, with no 99Tc-MDP-associated adverse reactions, and can shorten the period of corticosteroid treatment.