Ameloblastoma (ABL) and keratocystic odontogenic tumor (KOT) are benign odontogenic tumors with local aggressive behaviors. The purpose of our study was to compare MMP-1, MMP-9 and tenascin staining patterns between "aggressive" ameloblastoma / keratocystic odontogenic tumors and "nonaggressive" radicular cysts (RC)/ dentigerous cysts (DC). Ameloblastoma, keratocystic odontogenic tumor, radicular cyst (RC) and dentigerous cyst (DC) specimens were chosen from the archives of Gazi University Faculty of Dentistry, Department of Oral Pathology, and immunohistochemically stained with MMP-1, -9 and tenascin antibodies. The immunohistochemical expressions were noted and statistically analyzed. The ABLs and KOTs showed significantly higher MMP-1 and -9 positivity than the RCs and DCs (p<0.05). The ABL and KOT basement membranes showed more continuous tenascin expression. Tenascin intensity was significantly higher in the ABLs and KOTs compared to the RCs and DCs (p<0.05). The results suggest that higher expression of MMP-1 and -9 may play an essential role in the growth and progression of these tumors. Continuous tenascin positivity may reflect strong connective tissue reaction against the invasive epithelial parts of ABLs and KOTs.