Modern approaches to investigation of biomacromolecules using mass spectrometry techniques, which have crucially changed during the last decade, are considered. The attention is focused on the peptide and protein identification methods based on Fourier transform ion cyclotron resonance mass spectrometry, which provide high resolution and high accuracy and which are being developed with active participation of the authors. The ultimate possibilities of mass-spectrometric techniques regarding the sensitivity and uniqueness of identification of protein molecules are analyzed. The bottom-up and top-down identification approaches are described, their advantages and shortcomings for determination of post-translational modifications of proteins are estimated. Various methods for quantitative analysis of mixtures of biomolecules using isotope labels and isotope dilution are considered. The bibliography includes 192 references.