Adenocystic carcinoma of orbit is usually originated from the lacrimal gland, and comprises above than 60% of all malignant tumors found in the lacrimal gland. It is highly invasive and spreads along the nerves and blood vessels. Two cases of adenocystic carcinoma of orbit discovered in the Han Yang University Hospital in January, 1975 and September, 1977 are presented. The first case is found in a 46 year old man who complained of right side exophthalmos, diplopia and impairment of eye movement. The tumor mass including eye ball with optic nerve are removed. The size of tumor mass measures 4×3×2cm in dimension, located on the superior and posterior side of the eye ball and extend along the optic nerve. The tumor mass shows ill defined from normal lacrimal gland, but which is clearly demarcated from eye ball by sclera. The tumor consists of irregularly shaped masses of cells in a rather scanty connective tissue stroma. Numerous cystic or a1veo1ar spaces are presented in the cell mass, giving rise to cribriform effect which is very characteristic feature of this neoplasm. The second case is found in a 29 year old woman whose chief complaints are right sided exophthalmos and a palpable mass. The size of tumor mass is 4×3×2cm, which is covered with thin capsule. Histologic findings are also quite similar to that of case 1