Blood concentrations of the satiety-inducing glucagon-like peptide-1 (GLP-1) were compared in 20 bulimic patients and 20 healthy controls to examine whether secretory impairment of the peptide could be involved in bulimia nervosa (BN). Basal GLP-1 concentrations were measured by means of an enzyme-linked immunosorbent assay (ELISA) in blood samples taken four times over a 12-h period (08.00h, 12.00h, 16.00h, 20.00h) and seven times over a 3-h period following administration of a test meal. Eating-related and non-eating related patients' psychopathological aspects were measured by the use of a battery of ad hoc rating scales (Eating Disorder Inventory-2=EDI-2, Bulimic Investigation test-Edinburgh=B.I.T.E., Montgomery-Asberg Depression Rating Scale=MADRS, Spielberger State-Trait Anxiety Inventory=STAI, Yale-Brown-Cornell Eating Disorder Scale=YBC-EDS). Basal GLP-1 values were higher in patients than in controls only in the blood samples taken at 16.00h, whereas no difference between patients and controls was observed in GLP-1 concentrations in response to the test meal stimulation. GLP-1 levels correlated positively with bingeing-vomiting frequency, with B.I.T.E. scores and the "bulimia" subitem scores of the EDI-2 scale, and negatively with the "ascetism" subitem score of the same scale.