Abstract The glycoprotein and glycolipid content of brush border and submicrosomal membranes from the mucosa of the rat small intestine was investigated. The microsomal preparations were treated to remove the “non-membranous” material before analysis. In all of the membranes nearly 80% of the carbohydrate was associated with the protein fraction, and 20% with the lipid fraction. The carbohydrate of the protein fraction consisted mainly of mannose, galactose, glucose, fucose, glucosamine and galactosamine. With the exception of ribose which was found only in the rough microsomal membrane all the other sugars were present in similar quantities in all the membranes. The sugars in the lipid portion of the membranes consisted primarily of galactose and glucose. Amino sugars associated with the lipid fraction were found in the brush border membrane but were nearly absent in the internal membranes. Sialic acid was low in the protein and lipid fractions of all membranes. When sodium dodecylsulfate–gel electrophoresis of the membrane protein fractions was performed, many protein and glycoprotein bands were revealed. Each membrane had a different electrophoretic pattern both with respect to protein and to glycoprotein. The data obtained from this study suggest that internal membranes as well as the brush border membranes of the intestinal cells contain glycoproteins and glycolipids.