Normal prostates from Copenhagen/Fischer F1 hybrid rats were removed at 14 months of age. After routine formalin fixation and paraffin embedding, the expression of seven oligosaccharide structures by prostatic epithelial cells was assessed by an examination of lectin binding sites before and after neuraminidase digestion. Con-A bound to plasma membranes as well as the cytoplasm of all cells, thus confirming the presence of complex-type glycoconjugates. However, only two other oligosaccharides, apart from Con-A, were freely expressed on epithelial luminal plasma membranes. These were the Type I structure (Ga1β1→3GalNAc-) identified by PNA-binding and (GlcNAcβ1→4GlcNAcβ1→4-)n identified by WGA. PNA, WGA, UEA-1 and SBA bound to the cytoplasm of almost all epithelial cells, although their intracellular distribution was not identical. DBF binding was not identified. ECG bound to only a very few cells and then only after digestion with neuraminidase when it was localised to the cytoplasm. Following removal of sialic acid groups by neuraminidase digestion, PNA-binding became more prominent, SBA-binding appeared localized to paranuclear intracellular vesicles and WGA binding sites were abolished. This study has now characterized the major oligosaccharide determinants expressed by rat normal prostatic epithelial cells and provides a baseline against which alterations occurring during ontogenesis and oncogenesis may be compared. © 1990 Springer-Verlag.