Renal hemodynamics (Inutest. CPAH) were studied in five adult volunteers infused on separate occasions with branched-chain amino acids (BCAA), a mixture of nonessential and essential amino acids of the same volume, osmolality and nitrogen content, and 0.9% saline solution. BCAA infusion caused moderate renal vasoconstriction, a slight increase of GFR and a progressive rise of the filtration fraction (FF), whereas the amino acids mixture induced a significantly higher increase of GFR and a state of renal vasodilatation without altering the FF. The volume expansion with 0.9% saline did not cause any notable hemodynamic modification except for reduced FF. This study demonstrates that whereas a state of hyperfiltration and hyperemia is specifically induced by an amino acid mixture independently of volume expansion and osmolar load, the administration of BCAA provides nitrogen without renal hemodynamic stimulation.