Introduction: The immediate  success rate of endovenous  occlusion of the great saphenous vein (GSV) and its durability after endovenous laser ablation (EVLA) was postulated to be the matter of a dose-response relationship to the amount of laser energy used. Patients  and  methods:  Patients  presenting  with  varicose  veins  with  incompetent  GSV scheduled for EVLA were randomized into Group A who received low linear endovenous energy density (low LEED), and group B who received high linear endovenous energy density (High LEED) using the new 1470-nm diode laser. Patients were followed up for 6 months for the durability ofGSV occlusion and the occurrence of unwanted side effects after the procedure. Results: Between April 2011 and May  2012, we treated 63 legs in 58 patients. We had no statistically  significant difference between the two groups regarding the occurrence of early post-operative side effects as pain, paraesthesia, and ecchymosis. Regarding ultrasound proven durability ofGSV occlusion after 6 months, data showed total occlusion of the treated GSV segment in 24 out of 32(75%)  legs in group A versus 30 out of 31(96.7%)  legs in group B. This data indicates a statistically  significant difference (P= 0.04) regarding the failure of treatment in the treated GSV segment in group A patients who had the Low LEED 35J/cm in comparison to group B patients who had the High LEED 50J/cm. Conclusion: The use of the 1470-nm diode laser radial fiber (ELVeS-radial kit) with a high laser energy dose (LEED 50J/cm) was optimum in achieving a durable GSVocclusion without a significant increase in unwanted side effects when compared to lower laser energy dose (LEED 35J/ cm).