This study examines the expression of some selected adhesion molecules likely to be important in the migration of leucocytes across the blood-retinal and blood-aqueous barriers in samples of normal human retina and choroid by immunoperoxidase staining. ICAM-1, LFA-3 and ELAM-1 were expressed on retinal endothelium and ICAM-1, ELAM-1 and CD44 in the region of the external limiting membrane. VLA-2 was found around the retinal ganglion cells and in the inner and outer fibre layers and is likely to be important in maintaining the structural integrity of the retina. The endothelium on the choriocapillaris showed moderate staining of ICAM-1, and slight staining of LFA-3 and ELAM-1. These molecules may have an important functional role in the pathogenesis of many immunological ocular conditions, including uveoretinitis and corneal allograft rejection.