OBJECTIVE: The purpose of our study is to understand the compression, by subcutaneous fat in obese patients, who present a chronic increase in abdominal pressure, and on the sapheno-femoral cross. Such increase would result in a chronic venous insufficiency (CVI) of lower limbs and, if possible, it will be quantified also according to the posture. MATERIAL AND METHODS: We studied two different groups of patients with CVI: obese and non-obese. The severity of CVI was classified with the CEAP classification or by the standards of recent classifications. Abdominal pressure, by means of Kron’s method, and anterior-sagittal diameter were measured in some of the non-obese patients (4 males and 4 females) and in all the obese patients. The diameter of the femoral vein of both groups of patients in supine, sitting and standing positions was also measured. RESULTS: We found a higher incidence of CEAP 5-6 classes in the obese group than in the non-obese one; we also saw a higher incidence of classes 1-2 in the non-obese group than in the obese one. Moreover, Kron’s method showed a significant difference in abdominal pressure in relation to the BMI and the increase in the femoral vein diameter appears to be related to the weight and to the position. DISCUSSION: It was clear that the clinical manifestations of CVI are more severe in obese than in non-obese patients. Obesity in our study clearly acts with a continuous compressive action on the veins of the abdomen and thereby on the femoral vein, further contributing to a retrograde flow. So we tried to quantify an entity that until now could only be assumed