The urinary noradrenaline (NA) and adrenaline (A) were determined by means of fluorometric assay with double wavelength technique in 12 volunteers who were asked to run over a distance of 800 m with moderate speed. The ereatinine concentration in urine was also monitored and taken to estimate the excreting function of kidney during exercise. The heart rate (HR) and blood pressure(BP) were simultaneously measured. During the period of running 1) The ratio of urinary NA to creatinine and that of A to creatinine (NA or A ng/creatinine mg) increased significantly by 215% and 97%, respectively. The HR and BP elevated by 92% and 20%, respectively. The urinary NA was still markedly high in the recovery period. 2) While the urinary level of A had come back to normal range. The change in HR was directly related to the urinary NA but not to A level. The excreting function of kidney was markedly reduced by exercise. 3) The data of urinary NA and A expressed as the ratio (NA or A ng/creatinine rag) were recommended. The estimation of urinary NA is the most sensitive approach to measure the extent of regulatory mechanism in the response to physical training.