Phenylpyruvic acid is the organic compound with the formula C6H5CH2C(O)CO2H.

[citation needed] It is a product from the oxidative deamination of phenylalanine.

When the activity of the enzyme phenylalanine hydroxylase is reduced, the amino acid phenylalanine accumulates and gets converted into phenylpyruvic acid (phenylpyruvate), which leads to 'Phenylketonuria (PKU)' instead of 'tyrosine' which is the normal product of phenylalanine hydroxylase.

[1] It has been prepared by condensation of benzaldehyde and glycine derivatives to give phenylazlactone, which is then hydrolyzed with acid- or base-catalysis.

[3][4] Reductive amination of phenylpyruvic acid gives phenylalanine.