AIM: Research of a starting point to debate about the possibility of identifying a unique sign of previous DVT. MATERIAL OF STUDY: A retrospective study involving 202 outpatients with venous insufficiency of the lower limbs (CEAP classes C 4/6), classified according to the affected venous district. Patients positive for deep vein thrombosis (DVT) were subjected to Compression Ultra Sound test (CUS test) with measurement of the wall thickness at the point of formation of the thrombus and at fixed points of common femoral and popliteal veins used also in the patients with negative history of DVT. RESULTS: Among total group, only 19 patients (9.40%) had an history of DVT. No one of them had a superficial incontinence. The measurement of wall thickness in positive DVT history patients (group A) resulted in an average value of 1.10 mm (s.d=0.06), while the average value obtained in negative DVT history (group B) was 0.55 mm (s.d.= 0.20). However, in 13 patients wall thickness was > 1mm (mean: 1.04 mm). The difference between the averages of group A and B was statistically significant (p <0.05). DISCUSSION: In all positive DVT history patients and in 13 ones with negative history we found an increase in wall thickness, with a value > 1 mm. Can the wall thickening more than 1 mm be considered an indicator of previous DVT? Can it be considered a “marker” for thrombophilia status? CONCLUSIONS: The usefulness of a sign of previous DVT (even if asymptomatic), detected during a routine Doppler ultrasound check of lower limbs, could be a warning bell to investigate thrombophilia status.