Objective: To measure the distribution of valves in the long saphenous vein. Design: Morphological study of the intervalvular distance of the long saphenous vein. Setting: Department of Morfología, Facultad de Ciencias de la Salud (Universidad de Las Palmas de Gran Canaria, Spain) and Academic Vascular Surgery Unit, St Mary's Hospital, London, UK. Material: Twenty lower extremities from adult cadavers with no evidence of lower limb venous disease. Methods: Anatomical dissection of the long saphenous vein, with accurate measurement of valve distribution. Results: There were on average 8.7 valves in the long saphenous vein, with 6.3 above the knee and 2.4 below the knee. Conclusion: Contrary to classical anatomical texts on this subject there are more valves in the long saphenous vein in the thigh than in the calf.