In order to demonstrate the safety and efficacy of transnasal orbital decompression for malignant Graves' ophthalmopathy, we carried out a retrospective chart review and clinical follow-up examination of 78 consecutive patients who were operated on for compressive optic neuropathy (CON) with loss of visual acuity or visual field defects. The intervention – strictly transnasal, endoscopically controlled, bilateral decompression of the medial and inferomedial wall of the orbit – was performed when medical and radiation therapy had failed. A total of 145 endonasal decompressions were performed on 78 patients (63 female, 15 male, 52.2 ± 10.5 yrs.) over 9 years. Of these, 65 were operated bilaterally, 15 required only unilateral decompression; 4 had repeated surgery. Visual acuity increased from an average of 0.50 ± 0.27 (range, 0.01 – 1.25) to 0.75 ± 0.21 (range, 0.01 – 1.25). Proptosis decreased by an average of 3.94 ± 2.73 mm (range, –1.0 – 11.0 mm), from a mean preoperative Hertel measurement of 22.19 ± 3.13 mm (range, 15 – 34 mm) to a mean postoperative Hertel measurement of 18.3 ± 2.65 mm (range, 10 – 26 mm). Ocular motility was corrected by recession of the medial rectus muscle in 58 cases, in 26 cases immediately after decompression in the same surgical session. The transnasal orbital decompression procedure improved vision, decreased proptosis in a range comparable to more invasive techniques and had favorable cosmetic results without additional disfiguring by scars. Post-decompression strabismus was successfully managed by recession of both medial orbital muscles in the same surgical session.