We investigated the immunohistochemical expression of endothelial cell adhesion molecules in 17 cases of idiopathic inflammatory myopathies. The present study revealed: 1) a constitutive expression of ICAM-1, ICAM-2 and PECAM-1, but not VCAM-1, LFA-3 and E-selectin, on endothelial cells in normal muscles; 2) a modification of cell adhesion molecules expression in idiopathic inflammatory myopathies with an increased expression of the expressed molecules constitutively; an expression of LFA-3 and VCAM-1 on capillary endothelial cells in polymyositis/inclusion body myositis, these molecules being only observed on endothelial cells of some arterioles in dermatomyositis; 3) an expression of all these molecules on inflammatory cells in inflammatory myopathies. In dermatomyositis, the expression of ICAM-1 and VCAM-1, predominated on mononuclear cells located near vessels. In polymyositis/inclusion body myositis, a strong expression of ICAM-1, VCAM-1 and LFA-3 was present on inflammatory cells invading non necrotic muscle fibers; 4) absence of E-selectin on endothelial and inflammatory cells in all cases.