Infrared spectroscopy of biomolecules is one of the few methods, which combine a relatively simple measurements and a possibility of highly informative structural analysis. The most high-demand field of such investigations is the identification of various pathologies accompanied by changes in the biomolecular structure. In this study the comparative analysis of the secondary structure of blood serum proteins from patients with multiple myeloma and healthy donors was performed using infrared spectroscopy. There is a tendency for reduce the proportion of α-helices in the secondary structure of blood serum proteins in patients with multiple myeloma compared to healthy donors. Thus, infrared spectroscopy reveals difference in the secondary structure of blood serum proteins in patients with multiple myeloma and healthy donors.