This paper presents the results of experiments and mathematical simulation carried out to confirm the possibility of using holographic radar for the detection of breast tumors. In the work the software designed for the numerical solution of electromagnetic problems using the Finite-Difference Time-Domain Method. The simulation was performed with the three probe frequencies 4, 7 and 15 GHz. The model is a parallelepiped with dimensions 200×200×100 mm - mimicking the normal tissue of the breast, with the inclusion of a sphere - malignant neoplasm of breast tissue, the radius and depth of which have been varied. Frequency dispersion of normal and malignant tissues dielectric properties (conductivity and permittivity) was taken into account. It was shown both by theoretical and experimental results that it is preferable to use lower-frequency probing signal, namely, 4GHz, which can detect the inclusion of 5 mm diameter up to a depth of 10 mm. While using of probing signals of 7 and 15 GHz the depth limit of detection inclusion is not more than 5 mm, which is caused by the high attenuation in a medium. However, their usage is preferred because of higher resolution.