The genus Klebsiella contains a number of opportunistic pathogens which cause several serious infections, including pneumonia, bacteremia, and urinary tract infections. Characteristically, Klebsiella spp. produce large mucoid colonies because of the synthesis of large amounts of capsular polysaccharide (CPS). The LPS molecule is a virulence determinant in Klebsiella pneumoniae. In the present work from a pathogenic urine sample Klebsiella pneumoniae was obtained, the lipopolysaccharide extracted and completely purified by gel filtration chromatography. The purity was confirmed through determination of protein concentration and carbohydrate.