Monoclonal antibodies against the recombinant YB-1 protein were obtained and characterized. These antibodies are capable of specific detection of YB-1 protein in the enzyme-linked immunosorbent assay, Western blot analysis, and immunocytochemistry. Using phage display technology, a peptide interacting with the YB-1 protein was found. Based on monoclonal antibodies МАYB-1-2 and a peptide as part of the bacteriophage structural protein, a test system was developed for the quantitative determination of YB-1 protein in blood serum. The detection limit of the developed test system is 0.3 ng/mL.