Fimbriae play important role as pathogenic factors in many bacteria by their adhesive properties. Adhesin is located at the tip fimbriae but also in other parts of fimbriae. Recent findings on structure of fimbriae genes and their expression for the biosynthesis and formulation of complete fimbriae have been described. Special attention was focused on the participation of fimbriae in the mechanism of pathogenesis and their specificity towards tissue receptors. Most recent studies have been performed on E. coli and Klebsiella and those data predominate in this work. Fimbriae can be used for the construction of vaccine as a proteinous carrier for haptenic carbohydrate epitopes. In conjugates fimbriae express distinct immunogenic, adjuvant and protective properties.