Chronic venous diseases such as varicosis, post-thrombotic syndrome, and chronic venous insufficiency are among the most frequent clinical pictures in the Western world. The resultant consequences are persistent complaints such as a feeling of heaviness, tendency for swelling, and leg pain as well as vast skin changes culminating in an open leg ulcer. Although a series of past epidemiological studies are available, they are quite inconsistent with regard to implementation and definition of the clinical picture so that they cannot always be compared. Some are based solely on registration of disease history by questionnaires, which are inadequate to reliably assess actual prevalence. In only a very few studies are the results based on the actual examination of the subjects. Moreover, entirely difference age intervals and random samples are evaluated. The present study summarizes the most important epidemiological results with particular regard to the current Bonn Vein Study.