Tissue 02 tension is an important guide in detection of the general condition in critical patients. The tissue 0, is more difficult to measure with 0, sensor in skeletal muscle and subcutaneous tissues to present. But it is much easier to measure 0, tension in bladder urine with Censini catheter in Foley catheter than in tissue. We have measured 0, tension in bladder urine, main pulmonary artery and radial artery in 16 patients in chest surgical department of Yonsei University. College of Medicine from September 26 to December 22, 1981. Six patients were male and ten patients were female. Their ages ranged from 8 to 43 years. The correlation equation between the simultaneously measured PuO2 and PvO2 was found to be Ypvo2=4.04 + 0.88 Xpuo2 [r=0.88, p<0.0001] in regression curve with computer [HP/3,000, Program: SPSS] in the Yonsei University. Measurement of 0, tension in bladder urine and MPA will be rather simple, rapid and reproducible method than that of the 0, tension in tissues. But the speed of 0, consumption in urine is fast and so the 0, tensions in bladder urine were measured as soon as possible after they were collected. They were no complications or morbidity during measurement of 0, tension in these procedures except spontaneous removal of radial arterial cannulas in 2 patients.