Biological Behavior and treatment results of 33 patients with Adenoid Cystic Carcinoma (ACC) in the Head and Neck at Yonsei Cancer Center for 10 years between 1971 and 1980 were retrospectively analyzed. Most common, primary site was minor salivary glands such as maxillary sinus, nasal cavity and base of tongue. The typical biological behavior of these tumors was very slowly in growth with long rime of duration (mean 19 months) from I month to 10 years and more frequent of nerve invasion but rare invasion of neck nodes. Local control and failure pattern in the results of treatment, 16 of 17 patients with irradiation alone were seen complete or partial response but 5 cases of loco regional recurrence, 2 cases of failure of neck node and 4 cases of distant metastasis as lung and brain. On the other hand, among 10 cases of surgery and postoperative irradiation, 2cases of locoreginal failure and 3 cases of distant metastasis as lung and bone. 2 of 4 cases with surgery alone were recurred within primary site. Actuarial overall NED survival at 5 and 10 years were 52.6% and 42.8%, respectively. Survival rate of 10 patients with surgery and postoperative irradiation was more high than 17 patients of radiation alone. Therefore, we have known that surgery with postoperative adjunctive irradiation is most effective treatment modality of adenoid cystic carcinoma in the head and neck. Primary site, treatment modality and with or without nerve and bone invasion have influenced on prognosis.