Most recent research works on the hydrogen-bonded structure of solid 17O-labeled peptides and polypeptides by means of solid -state 17O NMR are presented. It has been demonstrated that 17O-labeling andsolid -state 17O NMR provide useful informations about the hydrogen-bonded structure between the amide oxygen and proton of peptides and polypeptides in the solid state, in addition to 1H, 13C and 15N techniques.