The expression of adhesion molecules on the vascular endothelium of healthy and inflamed human dental pulp was studied immunohistochemically using antibodies for selectin family and immunoglobulin super-family members. In healthy dental pulp, some vessels reacted very weakly with major histocompatibility complex (MHC) class II, and E- and P-selectin, and many vessels reacted with platelet-endothelial cell adhesion molecule-1 (PECAM-1), but no vessels reacted with intercellular adhesion molecule-1 (ICAM-1), ICAM-3 and vascular cell adhesion molecule-1 (VCAM-1). In inflamed pulp, a large number of vessels reacted strongly with MHC class II, E- and P-selectin, PECAM-1, ICAM-1, ICAM-3, and VCAM-1. This indicates that the vascular endothelium of the inflamed human dental pulp expresses diverse adhesion molecules for leukocyte emigration from the blood stream into tissue. Dental pulp is surrounded by dentin and isolated from other tissue, like an in vitro system, so dental pulp is an attractive model for studying the roles of adhesion molecules on the vascular endothelium in transendothelial migration of leukocytes.