BACKGROUND: Endovenous ablation of varicose veins using radiofrequency ablation (RFA) and endovenous laser therapy (EVLT) has reported advantages over traditional open surgical treatment. There is little evidence comparing the efficacy and patient-reported outcomes between the 2 endovenous solutions. This study compares the RFA and EVLT strategies in a prospective double-blind clinical trial. METHODS: Consecutive patients with primary unilateral great saphenous vein (GSV) reflux undergoing endovenous treatment were randomized to RFA (VNUS ClosureFAST) or EVLT (810-nm diode laser). The primary outcome measure was GSV occlusion at 3 months after treatment. Secondary outcome measures were occlusion at 7 days, postoperative pain, analgesic requirement, and bruising, assessed at day 7 after surgery. Quality of life (QoL) was assessed preoperatively and 3 months after surgery using the Aberdeen Varicose Vein Questionnaire (AVVQ) and EQ-5D. RESULTS: A total of 159 patients were randomized to RFA (79 patients) or EVLT (80 patients). Groups were well matched for demographics, disease extent, severity, and preoperative QoL. Duplex scanning confirmed 100% vein occlusion at 1 week in both groups. At 3 months, occlusion was 97% for RFA and 96% for EVLT; P = 0.67. Median (interquartile range) percentage above-knee bruise area was greater after EVLT 3.85% (6.1) than after RFA 0.6% (2); P = 0.0001. Postoperative pain assessed at each of the first 7 postoperative days was less after RFA (P = 0.001). Changes in the AVVQ (P = 0.12) and EQ-5D (P = 0.66) at 3 months were similar in both groups. CONCLUSIONS: RFA and EVLT offer comparable venous occlusion rates at 3 months after treatment of primary GSV varices; with neither modality proving superior. RFA is associated with less periprocedural pain, analgesic requirement, and bruising. REGISTRATION NUMBER: ISRCTN63135694 (http://www.controlled-trials.com).