The urines of 2 adult steers (circa 600 kgm.) were collected in 5 fasts of 5-14 days and the volume, total N, S distribution, and chlorides determined. In another 5-day fast after pasture and a 10-day fast after sub-maintenance feeding, the N distribution, acetone bodies, total fixed bases and titratable organic acids were also determined in the urines. In a 5-day and 6-day fast, respectively, of 2 younger steers (circa 250 kgm.), all the constituents were determined except chlorides, sulphurs and total fixed bases. The urines of the 5- and 10-day fasts were preserved by excess of HCl, which prevented changes in composition, particularly in the distribution of the nitrogenous constituents. There was a falling off in rate of elimination of urinary constituents, depending on the previous ration, with the exception of a rise in the inorganic sulphates and the increase in urea, determined only in fasts after sub-maintenance feeding. Calculation of the N partition showed a lowering of the amino-acid and hippuric-acid N percentage during fasting, an increasing urea-N percentage, and an approach in general to a N distribution, so far as ammonia, urea and creatinine are concerned, similar to that in men on a low N level. Striking results were the poor economy of the N metabolism of steers as indicated by the relatively high proportions of the total N as hippuric-acid N at the beginning of the fasts and on the resumption of food, and the absence of acidosis as shown by the low percentage of ammonia N and the small amounts of ketone bodies. The fasting base-line, or the disappearance of the effect of previous food, was reached by the 4th-6th day, as indicated by the constancy reached in this interval by the chlorides, phenols, fixed bases, organic acids and nitrogenous constituents.