A late complication of combined radiotherapy for malignoma of the inner genital tract is leg edema, whether of venous or lymphatic origin, which is not always clear. To analyse the influence of radiotherapy upon the pelvic and leg venous system, we performed sonographic caliber, occlusion plethysmographic and light reflexion rheographic measurements of veins in 32 patients prior and subsequent to irradiation. No statistically significant difference was found between mean values measured with the different methods. A clear deterioration of venous function was detected after treatment. Sonographic examinations of pelvic vessels after radiotherapy showed veins much less clearly outlined and with thicker walls, thus pointing to a direct connection between irradiation and edema of the vein wall. Whereas deterioration of the other parameters may also be explained by, for example, long periods of lying. Since according to our own observations, an insufficiency of the leg venous valves occurs relatively often, sometimes even years later, there is a clear correlation between irradiation and edema of the venous wall, with a slight deterioration of venous function detectable directly after irradiation. In order to prevent vein damage, prophylaxis of thrombosis and vessel topography should therefore always be considered when planning radiotherapy.