A canine inferior epigastric free flap was studied to determine the normal hemodynamic parameters in a free flap operation. Following revascularization, mean arterial blood flow in the vessels supplying the flap was 4.1 to 4.8 ml/min/100 gm of tissue. Meticulous suture anastomosis did not adversely affect mean flow. Furthermore, resistance in the flap did not change throughout the procedure. Further studies, using this and other models, are underway to examine the hemodynamics of failing flaps. The current study provides the baseline data necessary for this continuing work, which may provide an insight into preventive or therapeutic measures directed at improving free flap survival.