Mouse thymus-processed lymphocytes (T cells) sensitized against histocompatibility antigens can be specifically adsorbed on, and eluted from, fibroblast monolayers bearing these antigens. Not only normal, but also glutaraldehyde-fixed fibroblast monolayers can be used for specific adsorption. This shows that glutaraldehyde-fixed histocompatibility antigens can be recognized by specific receptors on T cells.