The cytochemical detection of acidic glycoconjugates located in rat gastrointestinal epithelia was performed using tissue sections embedded in Lowicryl K4M and cationic colloidal gold (CCG). CCG was prepared from poly-L-lysine and colloidal gold solution (10 nm). The staining of CCG was amplified after a photochemical silver reaction using silver acetate as an ion donor at the light microscopic level. The staining solutions adjusted to pH 2.5, CCG (2.5) and pH 1.0, CCG (1.0) were used for the characterization of carboxylated and sulfated glycoconjugates. At light microscopic level, CCG (2.5) stained several cell types of mucous cells in the rat gastrointestinal tract, while CCG (1.0) stained selectively mucous cells in gastric pits, glandular pylorus, upper crypts of the proximal colon and entire crypts of the distal colon. At the electron microscopic level, both CCG (2.5) and CCG (1.0) labeled the trans side of the Golgi apparatus and mucous granules in some mucous cells. These results are consistent with previous glycoconjugates histochemistry of the rat gastrointestinal tract at both the light and electron microscopic levels. CCG (2.5) and CCG (1.0) staining methods are useful and reliable postembedding staining procedures for the light and electron microscopic demonstration of intra- and extracellular acidic glycoconjugates.