Abstract 1.1. The acidity used by previous investigators was insufficient for quantitative precipitation of hippuric acid. 2.2. The amount of inorganic acid required for a quantitative recovery of hippuric acid varies with the composition of the urine and an excess of acid is desirable. 3.3. It was shown that the titration method is reliable as no other organic acids are precipitated with the hippuric acid. 4.4. A modified quantitative procedure is given in detail.