In order to understand the possible role of tyrosine metabolism and in particular that of elusive amines in the pathogenesis of eating disorders (ED), we measured the plasma levels of dopamine, noradrenaline, tyramine (Tyr) and octopamine (Oct) in a large group of anorexic and bulimic patients. In comparison to the control group, the levels of nordrenaline were significantly lower and those of dopamine and Tyr higher in the ED patients. The plasma levels of Oct were in the same range in both subject groups. However when comparing the bulimic vs. the anorexic group, the Oct levels were significantly lower in the anorexic group, whereas those of Tyr were significantly higher in the bulimic patients, suggesting that different activation in the metabolism of elusive amines may underlie the shift from the anorexic into the bulimic state. These biochemical findings raise the possibility that abnormalities of the limbic and hypothalamic circuitries play a role in the pathogenesis of ED. In addition, the very high prevalence of migraine (>75%) in our group of ED sufferers, and the biochemical profile(s) reported in migraine, which appear similar to that found in ED patients, suggest that migraine constitutes a risk factor for the occurrence of ED in young females.