The use of the short-time urine samples instead of 24hrs. urine is of very important significance for the estimation of the nutritional status of the groups or the individuals by biochemical methods, and in this study the analysis and the discussion were made about it. The urine samples were collected from 35 healthy women, 21 to 49 years of age, and the whole day urine was divided into 4 parts, morning (6-12), afternoon (12-18), night (18-24), and sleeping-time (0-6) urines. The urinary excretions of thiamine, riboflavin and N′-methylnicotinamide (MNA), as well as nitrogen and creatinine were determined, and interrelationship among them in each timed urine and also correlation between the intake and excretion were examined. The results were: (1) About the excretions of thiamine, riboflavin and MNA, 24-hour urine primarily correlated with sleeping-time urine. (2) Between the intakes and excretions of thiamine the highest correlation was found in the 24-hour urine, and secondarily in sleeping-time urine. Riboflavin also showed the similar tendency. (3) When expressed the urinary excretions of thiamine and riboflavin either per hour basis or per gram of creatinine basis, there was observed little difference in the coefficient of variation nor in the correlation between the timed urine and the whole day urine.