The extracorporeal respiratory support has (ECMO) or extracorporeal lung assist (ECLA). Jugulocarotid(JC) ECLA, which drains venous blood via the internal jugular vein and perfuses via the common carotid artery, is recognized as a therapeutic modality for acute respiratory failure of neonates. But recent follow-up studies report the possible neurologic complications after the ligation of the carotid artery. Femoro-femoral (FF) bypass is reported to be effective in cardiac support during cardiopulmonary resuscitation. Surgical approach of FF bypass is easier because of the superficial location of great vessels. To evaluate the cardiorespiratory support of FF bypass, twelve mongrel dogs were divided into JC and FF groups(n6 in each group) and ventilated artificially at F1O2 of 0.3 and 0.15 in a dog. While ventilating the oxygenator with N2 gas, control hemodynamic and blood gas values were obtained at FO1O2 0.3 and at F1O2 0.15. The values during VA ECLA in both groups were measured while flushing O2 gas into the oxygenator. We compared bypass flows and oxygenation effects between two groups. l) The comparison between JC ECLA and FF ECLA in F1O2 0.3 Mean arterial pressure (MAP) and cardiac output (CO) increased in both groups and mean pulmonary arterial pressure (MPAP) decreased in JC group. Bypass flow rates were 86±6ml/kg/min in JC group and 62±8 ml/kg/min in FF group. 2) The comparison between JC ECLA and FF ECLA in FO 0.15 MAP and CO increased in both groups and MPAP decreased in JC group. VA ECLA increased the arterial oxygen tension from 49±12 mmHg to 93±20 mmHg in JC group and from 54±14 mmHg to 77±12 mmHg in FF group. Bypass flow rates were 103±21 ml/kg/min in JC group and 67±12 ml/kg/min in FF group. The amount of changes of deltaPaO2(y) related to bypass ratio(x) was same between two groups The systemic oxygenation effect of FF ECLA in hypoxia was as efficient as that of JC ECLA. In conclusion, FF ECLA can be adopted for acute respiratory failure in which PaO2 is maintained about 50mmHg.