Adenoid cystic carcinoma (ACC) is a salivary malignant tumor with poor long-term prognosis, that is known to have predilection for invasion of the adjacent stroma and neural tissues. This carcinoma has shown a high incidence of recurrence and distal metastasis. Invasive carcinomas have been associated with the distributions of extracellular matrices (ECM). Cell proliferation as a marker of tumor growth has been related to poor prognosis in oral carcinomas. Immunohistochemical analysis of 15 cases of ACC was done using antibodies to laminin, type IV collagen, fibronectin, tenascin and anti-proliferating nuclear antigen (PCNA). Laminin and type IV collagen were totally or partially absent in the ACC invasive areas. Tenascin was expressed in the stroma and cytoplasm and was associated with tumor cell proliferation. It can be concluded that basement membrane represents a barrier that is lost during cell invasion and tenascin may be involved in the detachment of cancer cells, increasing the invasive potential of ACC.