AIMS: The efficacy of endoscopic endonasal orbital decompression in dysthyroid orbitopathy was analysed. METHODS: In 21 consecutive cases of bilateral operation short term (10 (SD 6) days after operation) and long term (156 (12) days after operation) results were recorded. RESULTS: Short term results showed that vision of the more affected eye improved from a mean of 0.35 to 0.59; vision improved in all but one eye which remained unchanged. In the fellow eyes mean visual acuity improved from 0.6 to 0.7; three of these eyes showed a decrease. Mean proptosis returned from 23.0 mm to 20.0 mm. As to motility the mean abductive capacity decreased from 5.5 mm to 4.0 mm of monocular excursion, whereas adduction increased from 7.5 mm to 8.5 mm. Upgaze and downgaze did not show any major change. The mean angle of horizontal squint shifted from 7.5 degrees of convergence to 15.5 degrees while no significant vertical or cyclorotational deviation was induced. These immediate postoperative results proved to be stable for the period of long term follow up with only slight changes. No significant bleeding or specific otorhinolaryngological complication without resolve occurred intraoperatively or perioperatively. CONCLUSION: This method is believed to be superior to non-endoscopic techniques because it avoids external scars and antral pain. With regard to the relief of intraorbital pressure, the technique gives good results for visual acuity improvement, but in proptosis reduction the method is not as efficient as external or combined procedures. There seems to be no difference when compared with other approaches in induction of horizontal squint. The method has a protective long term effect against the recurrence of compressive optic neuropathy.