To assess the oxygen utilization of extrauterine goat fetuses with arteriovenous extracorporeal membrane oxygenation via umbilical vessels, oxygen delivery (OD) and oxygen consumption (OC) were investigated in 19 long-term incubations (incubation periods 58-236 h). The OCs did not change (6.4 +/- 1.3 ml/min/kg, mean +/- SD, n = 227) when the ODs were more than 10 ml/min/kg, but were significantly suppressed when the ODs were less than 10 ml/min/kg. It was suggested that the oxygen metabolism of extrauterine goat fetuses is equivalent to that of fetuses in utero.