ObjectivesExternal valvuloplasty (eVP) is a reconstructive surgical method to repair the function of the terminal and preterminal valves. We evaluated the 6-month outcomes of eVP regarding the diameter of the great saphenous vein (GSV).MethodsPatients from five vein centres were included in this observational study. Follow-up involved detailed duplex sonography of the GSV. The venous clinical severity score (VCSS) and the C class of the clinical, aetiologic, anatomic and pathophysiologic (CEAP) classification were recorded.ResultsWe enrolled 210 patients, with a follow-up rate of 58%; eVP was sufficient in 95.24% of the patients. The GSV diameters decreased significantly from 4.4 mm (standard deviation (SD): 1.39) to 3.9 (SD: 1.12), 4 cm distal to the saphenofemoral junction (SFJ); from 3.7 mm (SD: 1.10) to 3.5 mm (SD: 1.02) at the mid-thigh; from 3.6 mm (SD: 1.14) to 3.3 mm (SD: 0.94) at the knee and from 3.1 mm (SD: 0.99) to 2.9 mm (SD: 0.78) at the mid-calf. VCSS decreased significantly from 4.76 (SD: 2.13) preoperatively to 1.77 (SD: 1.57) 6 months postoperatively.ConclusionsGSV function can be restored by eVP; diameters over the total length of the GSV decreased significantly.