In order to assess the effect of the addition of E. coli lipopolysaccharide (LPS) on the expression of tight junction proteins in the jejunum of weaned piglets (the animals were weaned at 21-days-old), 64 piglets were slaughtered at 1, 5, 7 and 10 days postweanig and complete extraction of jejunum was carried out in order to evaluate the molecular expression of Claudine 3 (C3), Claudine 4 (C4), and Zonula Ocludens-1 (ZO-1). To induce intestinal inflammation, animals were fed a basal diet supplemented with four levels of E. coli LPS (0, 0.3, 0.5, and 1.0 mg mg-1 of feed). The statistical design consisted of randomized blocks in a 4X4 factorial arrangement (four LPS concentrations and four post-weaning periods). A decrease was observed (P<0.01) in the expression of C3, C4, and ZO-1 in the animals that were fed the diet with the highest LPS-inclusion level. LPS contributes to the appearance of anatomical and intestinal functional disorders which are denoted by a decrease in the molecular expression of proteins from the intestinal barrier. This, in turn, is associated with an indiscriminate paracellular transport of molecules, microorganisms, and toxic compounds into the circulatory system. This results in post-weaning diarrhea and a decrease in the productive efficiency of piglets.