Renal percent clearance ratios for various electrolytes were determined on nine clinically normal Holstein heifers. Endogenous creatinine serum and urine levels were used to calculate the ratios. The average percent clearance ratios and standard deviations of Na, K, Cl, P, and Ca were 1.97+/-0.63, 49.3+/-9.2, 3.16+/-1.l2, 15.6+/-14.3, and 1.38+/-1.41, respectively. The correlation between Na and Cl percent clearance ratios within a sample was 0.92. A very strong direct correlation of urine creatinine and urine specific gravity was demonstrated.