The effects of severe protein malnutrition on the morphometry of the intestinal wall in the jejunum of adult rats were evaluated in this study. Six 90-day-old Wistar rats (Ratios norvegicus) were assigned into two groups: CG (Control Group, n = 3) and MG (Malnourished Group, n =- 3). CG animals were fed a 26%-protein chow whereas controls were fed a 4%-protein chow. After 90 days, part of the jejunum was collected and subjected to routine histology. HE-staining and histochemical techniques - Periodic Acid Schiff (PAS) and Alcian Blue (AB), pH 2.5/pH 1.0 - were used for the detection of glycoconjugates in 4 mu m -thick transverse cuts. Morphometric analysis of the HE-stained cuts revealed a decrease of the total thickness of the jejunal wall, mostly on the following layers: external muscle and mucosa - enterocyte height also decreased. Cuts stained by using histochemical techniques for the detection of glycoconjugates revealed maintenance of goblet cells reactive to PAS and AB pH 2.5, whereas the number of cells reactive to AB pH 1.0 increased. Protein malnutrition was concluded to provoke severe atrophy of the jejunal wall and an increase of sulphomucin secretion within the intestinal epithelium.