The inferior epigastric venous flap of the rat was chosen for experimental studies of vascular flow alterations. The long saphenous vein was not selected for use; preliminary studies involving forced retrograde injection demonstrated that it drains blood primarily from the leg and foot, not from its overlying skin. Eight different flap designs were studies: group A, saphenous flap, simple isolation with pedicle; group B, inferior epigastric flap, simple isolation with pedicle; group C, inferior epigastric flap, simple isolation with interpositioned Silastic sheet; group D, cross-transferred venous pressure arterial flap; group E, cross-transferred, arterialised venous flap; group F, arterialized venous flap, in which arterial blood was shunted away via the main vein: group G, cross-transferred venous pressure venous flap; and group K. control, nonvascularized flap. Three more groups (H, I, J) were introduced by repeating the flap designs of groups E, F, and G but preceded by forced perfusion of the venous system using 5 cc of normal saline at 200 mm Hg. The best results were obtained with groups B, C, E, H, and I. The other flaps necrosed. The results are discussed based on the assumption that true retrograde venous blood flow does occur.