troxerutin, a trihydroxy-ethyl-rutoside, in the venous wall have been studied in patients undergoing long saphenous vein surgery. Troxerutin, an autofluorescent drug, is currently used to relieve oedema and subjective symptoms in patients with chronic venous insufficiency. In order to determine the localization of the troxerutin, a confocal scanning laser microscope has been used to record the fluorescence from vein cross sections. The quantified fluorescence was used as a measure of the local concentration of troxerutin. In order to reduce the effects of local variation, several images have been scanned from each specimen. Then the recorded data have been analysed to see how the fluorescence varies in the radial direction within the venous wall. Results showed that troxerutin was significantly accumulated in both inner and outer parts of the venous wall. Whereas inner wall troxerutin uptake resulted from direct diffusion through the lumen, the outer wall uptake proceeded likely from the vasa vasorum circulation.