A simple method is described for the simultaneous determination of vanilmandelic acid (VMA), 3,4-dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindole-3-acetic acid (5-HIAA) and homovanillic acid (HVA) in urine. The compounds are isolated by a one-step sample clean-up on Sephadex G-10, separated by