The amputated hindquarters of adult female rats were infused with solutions of lactated Ringer's, Collins hypertonic renal perfusate, and dextran-dextrose on a washout and continuous basis. The perfusate was analyzed for energy compounds and breakdown products and the muscle tissue examined histologically. Intermittent perfusion or injection under pressure led to marked edema in a 4-hour period and was abandoned in favor of a system that perfused the part at 120 to 150 cm H2O. The model perfused with Collins gained an average of 1.35 gm, that with lactated Ringer's 2.35 gm, and that with dextrandextrose lost 2.35 gm. Pressure graphs of the various solutions indicated that the vascular bed reacts more physiologically to Collins solution and dextrandextrose than to lactated Ringer's. Histologic sections of the muscle biopsies confirmed this. The release of ATP and hypoxanthine with lactated Ringer's suggests that it is the most damaging of the perfusates. These findings support the results of the pressure graphs and histologic studies. A potential for replantation of amputated limbs that contain muscle when the cold ischemia time may exceed 6 hours is suggested by the data presented.