We investigated a peripheral serotonergic marker, i.e. platelet tritiated imipramine (3H-IMI) binding sites, which are part of the 5-HT transporter complex similar to that present in the brain, in 20 patients affected by coeliac disease (CD), as compared with 20 healthy controls. Platelet membranes and 3H-IMI binding were carried out according to a standardized protocol. The results showed that coeliac patients had significantly lower 3H-IMI binding sites than controls. This finding would suggest the presence of a dysfunction at the level of the 5-HT transporter that might underline the psychic disturbances frequently observed in coeliac patients.