We have modified resin embedding methods to provide optimal information from endoscopic biopsies. Mucosal biopsies were fixed either in buffered formalin and processed for embedding in Araldite or in acetone containing protease inhibitors and embedded in glycol methacrylate (GMA). GMA embedding generated an immunophenotypic profile similar to that obtained in frozen sections while yielding far superior morphology and greater numbers of sections from small biopsies. The phenotypic markers included those for T cells, macrophages, mast cells, eosinophils and neutrophils. We have also demonstrated collagens, cell adhesion molecules and integrin molecules. Sections of similar quality were obtained with Araldite but the repertoire of antibodies was restricted to those which can be applied to formalin fixed, paraffin embedded tissues. We suggest that for optimal results, small biopsies to be subjected to immunochemistry are fixed in acetone at -20 C with the inclusion of protease inhibitors and embedded in GUIA with careful temperature control.