Features of charge transfer and dielectric relaxation processes in blood serum samples of patients with oncohematological diseases and healthy donors were investigated by dielectric spectroscopy method. The observed features of the dielectric spectra for donors and patients, namely the decrease in conductivity in the high frequency region, the correlation between the degree indicator s and the total protein content, as well as changes in the spectrum of relaxation complexes indicate a change in the quantitative ratios of blood components in the presence of disease. This system rearrangement is the result of the fact that conformation of proteins (albumins and immunoglobulins) for patients is change. Keywords: Dielectric spectroscopy, serum, chronic lymphocytic leukemia, multiple myeloma, charge transfer, dielectric relaxation.