We analysed the results of extraocular muscle surgery in 38 patients with stable Graves' ophthalmopathy. Fixed sutures were used in all patients. A useful field of binocular single vision was achieved in 27 patients (71%) after one operation and in seven patients (18%) after more than one, whereas double vision was persistent in four (11%). No recurrence of diplopia was seen during one year of follow-up. No differences were found in duration of eye disease, angle of deviation, or in prior forms of treatment between patients who responded well to a single operation and those who needed more surgical procedures or those who responded less well. We conclude that, although the individual outcome cannot be predicted, every patient with diplopia and stable Graves' ophthalmopathy has an 89% chance of binocular single vision after extraocular muscle surgery. Prior treatment does not appear to influence this outcome.