After infusion of 250 ml of essential L-amino acids, plasma levels of α-amino nitrogen (α-AN<sub>2</sub>) in six chronic renal failure (CRF) patients were not different from those in six carefully matched control (CON) subjects. Plasma insulin increments increased significantly within both groups but were higher in the CRF group (p < 0.05 at 40 min, p < 0.005 at 55 min). Growth hormone levels were also higher in the CRF group. Previous studies have shown delayed clearance of plasma α-AN<sub>2</sub> after casein hydrolysate infusion, despite similarly increased insulin and growth hormone levels in CRF patients. We conclude that essential amino acids are probably more easily metabolized than casein hydrolysate in uremic subjects, but that normal metabolism occurs at the expense of higher plasma levels of insulin and growth hormone.