We studied amino acid concentrations in granulocytes and plasma of 24 children with chronic renal failure and 15 healthy children. Granulocytes were isolated from 10 ml of blood using a dextran-Ficoll-Hypaque procedure. Intracellular levels of leucine, isoleucine, methionine, phenylalanine, lysine, histidine, tyrosine, and arginine were significantly lower in children with chronic renal failure than healthy children. There were no significant differences in intracellular and plasma amino acid concentrations between children with chronic renal failure on a well-balanced protein-restricted diet and children with chronic renal failure with a normal protein intake.