The present invention provides an effective method for the production of optically active N-aryl-.beta.-amino acid compounds, which at the same time is suitable for industrial production. In the method of the present invention optically active sulfonylated .beta.-hydroxycarboxylic acid compounds, which are readily derived from .beta.-keto carboxylic acid compounds, are reacted with aromatic amines to produce optically active N-aryl-.beta.-amino acid compounds.