Dopamine-3-O-sulfate (DA-3-O-S) and dopamine-4-O-sulfate (DA-4-O-S) are important end products of L-dopa metabolism. Therefore they may give indications of disturbances in the peripheral metabolism of catecholamines, when measured in urine samples of patients with Parkinson's disease (PD). In addition, information about the reliability of DA sulfatation after L-dopa therapy may be of significance for its role in the elimination of DA from the peripheral nervous system. Although DA-3-O-S appears to be the predominant sulfo-conjugate in urine, there are no changes in PD nor in depression syndrome compared to controls with or without other neurological disorders. By contrast, DA-4-O-S is significantly decreased in de novo PD subjects. However, a similar reduction is notable in patients with other neurological disorders. In depressed persons the loss of this compound was less pronounced as compared to de novo PD. Treatment with combined L-dopa therapy caused increased excretion of DA-3-O-S, while changes in DA-4-O-S were only marginal. It is concluded that urinary DA-3-O-S cannot be used as marker for PD, while DA-4-O-S is significantly reduced in a variety of neurological disorders and in particular in de novo PD. Further studies are necessary to elucidate its role as possible peripheral marker to distinguish preclinical PD and depression syndrome.