A 61-year-old man with a history of sinus polyposis and prior sinus surgery presented with left-sided retrobulbar pain and headache. He was found to have left-sided proptosis, and imaging studies showed a large left medial orbital soft-tissue mass. Incisional biopsy revealed adenoid cystic carcinoma. Further evaluation revealed extensive sinonasal adenoid cystic carcinoma. The patient underwent en bloc maxillectomy with orbital exenteration and partial rhinectomy, followed by radiation therapy. The medial orbit is an unusual location for adenoid cystic carcinoma, which the authors believe was a secondary manifestation due to perineural spread from the sinuses via the ethmoidal nerves. Adenoid cystic carcinoma should be included in the differential diagnosis of tumors of the medial orbit, especially if there is a history of sinonasal disease.