Painful bilateral ophthalmoparesis, marked proptosis, increased intraocular pressure, and blindness developed in a 29-year-old woman with protein C deficiency and catastrophic antiphospholipid syndrome. Magnetic resonance imaging of the orbits showed bilateral proptosis, globe tenting, and tethering of the optic nerves consistent with an orbital ischemic syndrome. Despite aggressive therapy for antiphospholipid syndrome, the patient died. The autopsy showed necrosis of orbital tissues. This is the first report of orbital ischemic syndrome from protein C deficiency and antiphospholipid syndrome.