The authors propose a modification of endovasal laser obliteration (EVLO) of compromised great saphenous veins that differs from the standard method as described by L. Klein by the application of a cooled ozonated physiological solution (COPS) as a means for tumescence. The solution is administered under continuous ultrasound control into the fascial sheath of the vessel subjected to blood coagulation and the surrounding subcutaneous fat. A total of 86 patients were treated with the use of the newly proposed method. Irreversible occlusion of the compromised saphenous veins was achieved in 97% of the cases. The anti-inflammatory action of COPS allowed the development of adverse reactions typical of EVLO to be avoided in 100% of the patients.