We describe a method of isolating and quantitating the nucleotide compounds of the renal cortex and inner medulla. Nucleotide concentrations were determined under conditions of saline administration, hydration and hydropenia. Adenosine phosphates were the dominant nucleotides and ATP equal in concentration in cortex and medulla in µmoles/g solids. AMP was abundant only in the cortex and was reciprocally related to the quantity of ATP. We cite this in evidence of adenylate kinase activity in the cortex. Concentrations of ATP/g solids were equal in both cortex and medulla in hydropenia and hydration. Calculations of energy for sodium transport based on these data are offered.