Adenoid cystic carcinoma of the lacrimal gland is a highly malignant tumor usually characterized by symptoms of less than 1 year's duration. Computed tomographic (CT) findings of adjacent bony erosion or focal tumor sclerosis are also suggestive. We present a 57-year-old female patient who manifested symptoms of an enlarging mass in the right lacrimal fossa for almost 3 years prior to the establishment of the diagnosis of adenoid cystic carcinoma. CT findings during those years were not supportive for malignancy. The treatment included en bloc resection of the mass and adjacent bone and radiotherapy.