BACKGROUND Vision-threatening compressive optic neuropathy occurs in a minority of patients with Graves' orbitopathy. Surgical orbital decompression, systemic glucocorticoids and orbital irradiation are treatment options. Orbital decompression is being performed on an increasing number of patients for other indications such as corneal exposure and disfiguring proptosis. OBJECTIVE To examine the outcomes of surgical orbital decompression for Graves' orbitopathy by one surgeon. METHODS An analysis of a retrospective case series of 88 consecutive patients (151 orbits) who underwent orbital decompression for Graves' orbitopathy between April 1991 and November 2002. RESULTS The indication for surgery was compressive optic neuropathy for 57 orbits; 94 orbits had an indication other than optic neuropathy. Of those with optic neuropathy, 94% had improvement or maintenance of visual acuity and 93% had improvement in colour vision after decompression. The overall mean reduction in proptosis was 4.7 mm. Of all patients, 30% had new or worsened diplopia postdecompression. Patients with optic neuropathy were more likely to develop new or worsened diplopia than those without optic neuropathy. CONCLUSIONS Orbital decompression is a safe procedure and effective in improving vision in compressive optic neuropathy. It is effective in reducing proptosis, therefore improving exposure keratopathy and cosmesis. However, new or worsened diplopia is a significant postoperative complication, and subsequent strabismus surgery might be required. This is an important consideration, especially for patients undergoing surgery for non-optic neuropathy indications.