The histological localisation of á-D-galactopyranosyl residues in glycoconjugates of rat stomach and duodenal mucosae is studied by use of Griffonia simplicifolia agglutinin I, i.e. the isolectin mixture (A+B) and the isolectin B4 (B4). Cryostat sections which are either unfixed or acetone fixed and paraffin sections from both ethanol-acetic acid and formalde-hyde fixed tissue blocks are compared. Also, the staining efficiency of fluorescein (FITC), horseradish peroxidase (HRP) and colloidal gold particle (CGP) labels in both direct and indirect lectin stainings are studied.