Adenoid cystic carcinoma is malignant tumor in salivary gland, and its behavior is very invasive. Of all malignant tumor adenoid cystic carcinoma is occured in frequency of 4.4% in major salivary gland, and 1.29% in minor salivary gland. Histopathologically, adenoid cystic carcinoma is characterized by a cribriform appearance, and tubular form and solid nest type tumor can be seen. The tumor cell structure composed of modified myoepithelial cell, and basaloid cell. Extracellular matrix of this tumor cell contains variable ground substance with basement membrane component. Basement membrane matrix composed of collagen fibers, glycoproteins, proteoglycans, and its function is well known that it participate in differentiation, proliferation, and growth of tumor cell. Basement membrane molecule is essential for invasion of peripheral nerve, blood vessel, skeletal muscle in tumor cell of adenoid cystic carcinoma. In many studies, the tumor cell of adenoid cystic carcinoma containing modified myoepithelial cell participate in synthesis of proteoglycan. In this study, tissue sample of adenoid cystic carcinoma of human salivary gland were obtained from 15 surgical specimen, and all specimen were routinely fixed in 10% formalin and embedded. Serial 4-micrometer thick sections were cut from paraffin blocks. the histopathologic evaluation was done with light microscopy. And, the immunohistochemical staining, characteristics of glycosaminoglycan were observed. For biochemical analysis of glycosaminoglycan, isolation of crude glycosaminoglycan from tumor tissue and Western bolt analysis were carried out. With transmission electomicroscopy, tumor cell were observed. Biologic behavior of adenoid cystic carcinoma was observed with distribution and expression of basement membrane of glycosaminoglycan in tumor cells, The results obtained were as follows: 1. In immunohistochemical study, chondroitin sulfate is postively stained in tumor cell and interstitial space, dermatan sulfate is weakly stained in ductal cell. But keratan sulfate is negatively stained. 2. In immunohistochemical study, heparan sulfate is strong positive stained in tumor cell and basement membrane, especially in invasion area to peripheral nerve tissue. 3. In transmission electromicroscpic view, the tumor cells are composed modifed myoepithelial cells, and contains many microvilli and rough endoplasmic reticulum. 4. In Western blot analysis, the expression of glycosaminoglycan is expressed mostly in heparan sulfate. From the results obtained in this study, tumor cell of adenoid cystic carcinoma is composed modified myoepithelial cell, and glycosaminoglycan of basement membrane molecule of heparan sulfate and chondroitin sulfate mostly participate in the development and invasiveness of adenoid cystic carcinoma by immunohistochemical study and western blot analysis.