AIMS. 1) To evaluate epidemiological data (age, gender, initial complaints, and ophthalmic findings) of a patient cohort with a primary or secondary orbital meningioma. 2) To evaluate the clinical course of these patients. 3) To evaluate the outcome of treatment. PATIENTS AND METHODS. All consecutive patients with a presumed meningioma with orbital involvement seen at the Academic Medical Center, Utrecht, in the period 1/1/1992-31/12/1999 were evaluated retrospectively. RESULTS. Sixty-three patients with either an optic nerve sheath (n = 16) or a sphenoid ridge or tuberculum sellae meningioma (n = 47) were seen (mean age: 41.9 and 47.6 years, respectively); 20 of these had been treated neurosurgically previously. Fifty-three were females. The most frequent initial symptoms in both groups were proptosis and visual complaints. Thirty-three patients were followed without treatment, eight of them showing a lingering worsening of vision and a slow increase of tumor mass. Thirty patients were operated for different reasons (to confirm the diagnosis, or because of decreasing vision, disfiguring proptosis, threatening of the optic chiasm, or severe retrobulbar pain). Life-threatening problems did not occur, cranial nerve damage being the most frequent complication. Macroscopic radical tumor resection was only obtained in about 50% of the operated patients, but immediate (partial) relief of subjective complaints was obtained in up to 90%. A recurrence with clinical symptoms was seen in two patients within the relatively short follow-up period. CONCLUSIONS. Proptosis and, secondly, vision complaints are the most frequent symptoms in patients with either a primary or a secondary orbital meningioma. Their clinical course is extremely variable. Loss of vision is frequently seen in both groups. Orbitoneurosurgical meningioma resection has a high immediate success rate. Damage to cranial nerves is the most frequent complication of meningioma resection.