Daflon 500 mg (S-5682) is a purified, micronized flavonoid fraction containing 90% diosmin and 10% hesperidin that is currently used to treat chronic venous insufficiency and hemorrhoidal disease. Thus, it seemed of interest to evaluate the effects of S-5682 on ischemia/reperfusion, ie, the changes in mean internal diameter and blood flow of arterioles and venules and the functional capillary density (FCD) during reperfusion after ninety minutes of total ischemia in the hamster cheek pouch microvasculature. Different doses of S-5682 (5, 20, 80, and 160 mg/kg body weight/day), suspended in 10% lactose solution or vehicle (10% lactose) were administered orally to male hamsters for ten days twice a day. The cheek pouch preparation was placed under an intravital microscope coupled to a closed-circuit TV system. A ninety-minute local ischemia was obtained by a cuff mounted around the neck of the everted pouch where it left the mouth of the hamster. Mean arteriolar and venular internal diameters were determined by means of an image-shearing device, IPM model 907; red blood cell (RBC) velocity was measured by the dual-slit photometric technique; microvessel volume flow was calculated from diameters and RBC velocities; and FCD was defined as the number of red-cell-perfused capillaries per observation field. During reperfusion, placebo-treated animals showed significant vasodilatation concomitant with a decrease in blood flow and FCD compared with preischemic values and an impairment of the myogenic response. In S-5682-treated animals, there was a significant dose-dependent improvement in all these parameters including the myogenic tonus. These results clearly demonstrated that oral administration of different doses of S-5682 for ten days improved the microvascular reactivity and FCD after ischemia/reperfusion in a dose-dependent fashion in the hamster cheek pouch microvasculature.