Background Assess the safety and effectiveness of indirect radiofrequency ablation (RFA, Closure FAST) for the treatment of incompetent great saphenous veins (GSVs) with type 1 aneurysms. Methods This was a retrospective analysis performed in three centers (2007–2021). All patients presenting with saphenous aneurysms close to the junction (within 2 cm) were included. They were treated with RFA. Phlebectomies and/or sclerotherapy were performed during the same treatment session. Duplex ultrasound (DUS) was performed early after the procedure and then, more than a year later. Results Eight patients (11 limbs) were included between June 2007 and May 2021 with a median diameter of the GSV aneurysm 21 mm (IQR 17.2–23.4). No severe adverse events occurred apart from one endovenous heat-induced thrombosis (EHIT) class III (9.1%). After more than a year (mean 7.2 ± 4.2, median 8 years), none of the aneurysms was present on DUS and the truncal obliteration rate was 100%. Conclusion RFA appears to be a safe and effective treatment for patients presenting with incompetent saphenous veins with the type 1 aneurysm.