The expression and distribution of the extracellular matrix (ECM) in 37 gliomas and 19 meningiomas were studied immunohistochemically by antibodies to type 3, 4 and 6 collagen, fibronectin and laminin. In gliomas the expression of these antigens was more intense and thicker in the tumor vessel walls, and was positively correlated to the malignant degree of the gliomas. This suggests that the thickening of the vessel walls and the increase of their ECM components in gliomas may be one of the causes why gliomas are extremely rare to metastasize to the outside of the cranium. All the above-cited ECM were positive in the fibroblastic type of meningioma, being just located between the tumor cells; whereas in syncytial type they were negative. This indicates that the immunohistochemistry of ECM may be of advantage in differentiating meningioma type.