Our knowledge of the prevalence, pathogenesis, and treatment of primary great saphenous varicose veins has been reviewed. There is now evidence that potentially correctable environmental factors contribute importantly to the development of primary varicose veins, but what these factors are is not known. It is suggested that the evidence that incompetence of the venous valves at and above the saphenofemoral junction initiates the development of primary great saphenous varicose veins is scientifically weak. There are a number of questions about the treatment of primary varicose veins that have scarcely been asked, far less answered. The case is argued for microepidemiological studies of the prevalence of primary varicose veins, for studies to test more rigorously the valve hypothesis of their causation, and for more prospective, long-term, clinical trials of treatment to be undertaken.