Continuous transcutanous measurement of pO2 (tcpO2) has been adapted to fetal and neonatal use, utilizing a noninvasive miniaturized modified Clark pO2 electrode attached to the skin by adhesive. The unprepared ear of the adult female Flemish Giant rabbit was used for attachment of the electrode, and blood for arterial pO2 (apO2) was taken from the auricular artery. The rabbits were gently restrained and unanesthetized. The tcpO2 and pO2 were compared at environmental temperatures of 20–23, 50, and 60 °C, in separate experiments. The data demonstrated that tcpO2 is not the same as pO2. It is most clearly related to local blood flow. tcpO2 only indirectly reflects apO2 when peripheral flow is comparable to central flow. Proper use of tcpCh in the fetus and neonate requires cognizance of blood flow conditions for correct interpretation. tcpO2 is not indicative of apO2 when reduced peripheral circulation is present, in the rabbit ear.