Neural factors appear to play a major role in the pathogenesis of vitiligo. To investigate the possible correlation between vitiligo and peripheral monoaminergic system activity, we used high-pressure liquid chromatography and electrochemical detector methods to evaluate the basal urine excretion values of catecholamines [norepinephrine (NE), epinephrine and dopamine (DA)], their relative metabolites [3-methoxy-4-hydroxyphenylglycol (MHPG), normetanephrine (NMN), metanephrine (MN), vanilmandelic acid (VMA) and homovanillic acid], as well as 5-hydroxyindoleacetic acid (5-HIAA), in 35 healthy subjects and in 70 patients, suffering from non-segmental vitiligo at different stages of the disease. Levels of NE, DA, NMN, MN, MHPG, VMA and 5-HIAA were found to be significantly higher in patients than in controls. The patients with progressive vitiligo (n = 56) presented increased urinary excretion values for all parameters (in particular, NE levels) than other patients. Interestingly, in patients at its more recent vitiligo onset (<1 yr), NE values were different to those of subjects affected from 1 to 5 yr and from 6 to 10 yr. This result was confirmed by the significant negative relationship detected between NE excretion values and disease duration. In both vitiligo and control groups, significant correlations were found between monoamines as well as between these monoamines and their metabolites. The increase in catecholamine turnover, mainly occurring at the onset of the disease, is probably due to the stress associated with the appearance of lesions. Moreover, considering that these compounds readily produce toxic free-radicals and that vitiliginous subjects have a defective free radical defence mechanism, they may also contribute to the disappearance of melanocytes in the early phases of vitiligo.