Adenoid cystic carcinoma (cylindroma) usually arises from the salivary, lacrimal, or other exocrine glands, and is rarely encountered by neurosurgeons. The authors describe three cases involving intracranial extension. An intraorbital tumor in a 71-year-old man extended directly into the epidural space of the frontal base and destroyed the orbital roof. In a 53-year-old woman, the tumor arose from the area adjacent to the eustachian tube and invaded the Gasserian ganglion. In the third patient, a 58-year-old man, the tumor originated in the maxillary sinus and extended directly into the middle cranial fossa. In all these cases, the tumors were removed to the fullest extent possible. Although residual tumor was markedly reduced by radiation therapy, recurrence and metastases occurred within a few years. Thus, adenoid cystic carcinoma appears to be radiosensitive, but not curable by irradiation. In treating a recurrent tumor in one patient, we applied the so-called "two-route" chemotherapy (cisplatin and its antidote) in combination with radiation therapy. The tumor responded well to this therapy, although multiple pulmonary and bone metastases eventually led to the patient's death.