The aggressive behavior and potentially lethal nature of some hemangiopericytomas primary in the orbit are generally unknown in the field of ophthalmology. The neoplasm is not common in the orbit, and reports in the ophthalmic literature usually describe single-case examples of the neoplasm with short-term periods of observation. Two in our series of 11 patients died of metastasis 35 years after the onset of symptoms. Another patient died of local orbital recurrence with secondary invasion of the intracranial vault, which was possibly related to heavy radiotherapy. In the orbit, those neoplasms frequently are circumscribed in their growth. Complete and intact removal is recommended. If the tumors are incompletely excised, recurrences are frequent but may not be manifest as long as ten years after surgery.