Introduction. The involvement of pathological segmental venous hypervolemia of the lower leg in patients with varicose veins in the formation of chronic venous insufficiency (CVI) is an established fact, however, objective criteria for this pathohemodynamic phenomenon have not been definitively determined today.The purpose of the study. Determination by air plethysmography (APG) of the degree of functional disorders in the limb and establishment of significant criteria characterizing pathological segmental hypervolemia of the lower leg in patients with CVD of various clinical classes according to CEAP.Materials and methods. For the period from 2002 to 2019, 380 healthy individuals with no symptoms of chronic venous diseases and 896 patients with CVD were examined with the use of APG, with their distribution in accordance with the CEAR international classification as follows: C0–C1, C2–C3, C4–C6 clinical classes. To assess the intensity of venous blood flow, the following values were calculated: the maximum capacity of the leg veins (Venous Capacity – VC), the volume of their evacuation (Evacuation Volume – EV) for a set time, the maximum venous outflow (Maximum Venous Outflow – MVO), the ratio of these values on both limbs (Venous Capacity Index – VC1, Evacuation Volume Index – EVI, Maximum Venous Outflow Index – MVOI).Results. The most statistically significant and conjugate correlation data were obtained (expectation, mean square deviation, standard error of expectation, median and coefficient of variation) during the analysis in groups according to the characteristic VCI.Discussion. The obtained results allowed us to assert that APG is an informative functional method for diagnosing hemodynamic disorders in patients with lower limb CVD.Conclusion. The established criteria of the venous capacity index will allow in practice to give an objective characterization of the degree of change in hemodynamic disorders in patients with CVD before and after the treatment undertaken.