The conformations of H-Lys-Asp -OH and H-Glu-Lys-OH cyclic dipeptides were subjected to theoretical analysis by the method of atom-atom potentials with flexible geometry. Constants of spin-spin coupling of vicinal protons were calculated for the theoretical conformers of both dipeptides. CD and NMR spectra were measured for both peptides synthesized, and the calculated and experimental values of spin-spin coupling constants were compared. These coincided well for the dipeptide containing Asp residue, and we concluded that it exists in solution as one conformer. For the Glu-containing dipeptide, the existence of minor conformers, which increase the difference between experimental and theoretical spin-spin coupling constants, was shown to be possible.