While di-leucine hydrochloride precipitated from protein hydrolysates at pH 2.4 by NaCl contains only small amounts of methionine, leucine precipitated similarly at pH 6 contains appreciable amts. Curves are given showing the solubility of methionine in aqueous and saturated NaCl solns. at different pH values. The solubility of methionine in H2O at ordinary temp. is 4.95%; in saturated NaCl soln., 2.3%. A simple method for the isolation of tyrosine. leucine and methionine from protein hydrolysates is discovered. These amino-acids have been obtained in yields of 3%, 4.7%. 1.55%, respectively from casein; 1.35%, 6.1% and 2.5% from egg albumin.