1. 1. After a continuous infusion of [ 3H]leucine into conscious rats the 3H count in the acid soluble extract was significantly higher in kidney, heart and liver of adrenalectomized rats than in the controls. However, the 3H counts remaining as [ 3H]leucine were similarly low in all three tissues from both groups of animals. 2. 2. Application of the 14C-dansylation method revealed that the specific activity (dpm/nmol) of leucine in the tissue extracts of adrenalectomized rats decreased by 30% in kidney and liver and by 12% in heart. due to corresponding increases in the free leucine pools. 3. 3. Adrenalectomy also increased the isoleucine and valine content in kidney and liver and lysine and proline in the liver, but decreased the glycine content in kidney. 4. 4. Aldosterone treatment of rats had no effect on any of the changes caused by adrenalectomy.