**Electroplethysmography is a method for studying hemodynamics based on recording electrical potentials of the skin.** When pressure is created on the area under study, the veins stop functioning and blood clots appear, which leads to a change in the electrical resistance of the skin. The reflection of this process is typical for the electroplethysgraphic test. It is based on measuring the drop (or recovery) of the potential difference recorded in different areas of the skin or in one of the standard leads at different depths of electrode penetration. It is often called the “impedance reflex diagnostic method,” which indicates its applied focus on recognizing pathological changes and especially the latent phase of the disease in the preclinical period. For example, it was