The greater saphenous veins (GSV) are the best substitute for arterial in several locations and are often the only convenient graft. As patients consult for varicose veins at an increasingly younger age and since surgery for varicose veins has become quite popular, there is a risk of unneeded destruction of saphenous veins which will be lacking later. Approximately 80% of the GSV veins in patients consulting for varcosities are normal, slightly dilated or simply have one or more minor areas of dilatation. A special Dacron sheath can be used to maintain these areas of dilatation. The cases presented here demonstrate that these bypass remain patent and that non-sheated areas do not undergo undue dilatation. This technique makes it possible to widen the use of GSV in a larger number of patients with varicose veins. Consequently, it is necessary to verify the caliber of the trunk of GSV during the echo-Doppler examination before treating patients with varicose veins. Suitable GSV should be conserved during initial treatment. Patients should be well informed of the rationale for such decisions, especially concerning the chronological delay between the occurrence of venous varicosities and arterial disease.