Prevalence, risk factors, and complications of peripheral venous disease of the lower limb were examined in a prospective study on 1,000 unselected outpatients of a polyclinic. The investigation was planned as a representative epidemiologic study in the Munich area, with the intention of getting information on the sociomedical importance, therapy, and possibilities of prevention of peripheral venous disease. Prevalence. Of the patients examined 50% showed peripheral venous abnormalities, which were unimportant in 25%, relevant in 10%, and pathologic in 15%, i.e., one of seven patients had significant venous problems. No significant differences dependent on sex were found. The prevalence of peripheral venous disease grew with increasing age. Medical reliability. The striking sociomedical importance of peripheral venous disease was demonstrated by the high rate of complications, such as thrombophlebitis, chronic venous stasis, and embolism. Nearly every other person with pathologic venous changes suffered from thrombophlebitis, every 3rd from a chronic venous stasis, every 4th from ulcera of the legs and every 10th from embolism. Risk factors. Especially the varicose saphenous veins seemed to depend on risk factors such as overweight, standing position at work, herniae, flat and/or spread feet, familial disposition, age and pregnancy. In women and men peripheral venous disease proved to be very closely correlated with a positive familial disposition. In male patients there were further correlations with hernias and a standing position at work, and in women with flat or spread feet. Overweight, pregnancy or multiple pregnancies are recognized as aggravating factors with only tendentious correlations. The most important recommendation to people with peripheral venous disease is early medical treatment to prevent progressive disease. Complications can probably be markedly reduced by early treatment.