The aim of this study was to report the results of high-energy endovenous laser treatment to measure the relationship between the fluence and the outcome in terms of recanalization. In 97 patients, 129 great saphenous veins were treated with endovenous laser treatment, using a 980-nm diode laser. Follow-up visits were done at 3 days, 1 month, and 6 months. The best results were noted 1 month postoperative, but at 6 months, control late recanalizations occurred decreasing occlusion rate to 90.6%. Patients were divided into 2 groups according to the outcome (occlusion or recanalization) at 6 months, and statistical analysis was done. The authors found 52 J/cm(2) mean fluence in the occlusion group and 43.7 J/cm(2) in the nonocclusion group. This was a statistical significant difference (P < .01). The occlusion rate on long term is fluence dependent. But recanalizations might occur even in these higher fluence treatment groups. A fluence of 52 J/cm(2) is advised.