Endovenous ablation, using radiofrequency or laser, is becoming the mainstay of treatment for symptomatic varicose veins in the setting of saphenous vein incompetency. Both procedures have been shown to produce high rates of truncal vein occlusion with few complications. This article presents three patients who developed arteriovenous fistula (AVF) following great saphenous vein treatment: two following radiofrequency ablation (RFA) and one following laser ablation. This is the first published report of AVF following RFA for which operative details are known. We review the literature and discuss possible causes and management of this rare complication.