Urinary metabolites of catecholamines and indoleamines have been investigated in 16 patients with anorexia nervosa (AN) and 13 controls using a HPLC-method. Vanillic mandelic acid, 3-methoxy-4-hydroxyphenylglycol, homovanillic acid, 3,4-dihydroxyphenylacetic acid, 5-hydroxyindole acetic acid and indoleacetic acid were significantly decreased in the pre-treatment phase. In four patients long-term treatment including parenteral and enteral nutrition together with psychological methods resulted in an increase in the levels of these substances and this correlated with increased weight gain and urinary creatinine. It is concluded that both central and peripheral disturbances are involved in AN, particularly with regard to biogenic amine metabolism.