A 28-year-old man presented to the emergency room complaining of right proptosis. He also manifested eye pain and facial fullness and redness in this side. Seven years ago, he had right hemifacial gunshot trauma treated with surgical reconstruction. The CT scan showed expansion of the right maxillary sinus due to a hypodense nonenhancing lesion extending to the nasal cavity, masticatory space, and extraconal space of the orbit. MRI was performed showing high signal intensity of the lesion on T2-weighted images indicating a cystic nature. T1-weighted images also demonstrated high signal intensity of the lesion suggesting hemorrhage. At endoscopic maxillary antrostomy, the diagnosis of a chronic hematic cyst was confirmed. Chronic hematic cysts of the orbit should be included in the differential diagnosis of proptosis, especially if there is clinical history of past trauma. Due to the fact that physical examination is nonspecific, radiologic evaluation is useful to confirm the diagnosis and for presurgical planning.