A 48-year-old woman presented to the emergency department with swelling and erythema of the right upper eyelid for 4 days. Computed tomography showed a superiorly-based subperiosteal orbital abscess together with paranasal sinusitis. She was managed medically, but symptoms did not improve, so we drained the abscess using image-guided intranasal endoscopy. Her symptoms began to improve 2 days after drainage, and her recovery was uneventful. Drainage of an orbital subperiosteal abscess should be considered if there are ophthalmological symptoms such as visual disturbances, raised intraocular pressure, or proptosis of over 5mm. Various approaches are available, but endoscopic intranasal drainage was thought to be the most safe and effective. Image-guided drainage may help to minimise the extent and risk of operative complications.