Since the pathogenesis of endocrine ophthalmopathy is unclear, there has been little agreement on the treatment of the disease. The influence of thyroid surgery on endocrine ophthalmopathy is controversial. To evaluate the effect of thyroid surgery on the course of the disease, we developed a special ophthalmopathy index. As a standard procedure, subtotal thyroidectomy with thyroid remnants of 3-5 g was performed. A total of 176 patients with Graves' disease underwent the above treatment between 1986 and 1988. In 78 patients suffering from concomitant endocrine ophthalmopathy, ocular status was examined prior to operation and postoperatively. The history of endocrine ophthalmopathy had been present less than 2 years preoperatively in 74% of the patients. Follow-up ranged from 6 to 36 months. Postoperatively, 54 (69%) patients showed a marked improvement of their eye symptoms. In 18 (23%), there was no change and, in 6 (8%) patients, the severity of the eye symptoms increased after the operation. As a result of these data, a cautious and preliminary conclusion may be justified--that subtotal thyroidectomy may have a positive effect on endocrine ophthalmopathy.