An automated method for the determination of urinary 4-hydroxy-3-methoxymandelic acid is described. It is based on the procedure of Pisano et al (Clin Chim Acta, 1962; 7: 285-291). The correlation between the automated method and HPLC was high even though diet and medications were not restricted. The method has the advantages of short analysis time, specificity, and precision.