Untreated adult coeliac patients have previously been shown to have a high frequency of depressive symptoms as reported in a personality inventory (the MMPI). In the present study we determined the concentrations of three major monoamine metabolites in samples of lumbar cerebrospinal fluid of ten consecutive adults with newly detected coeliac disease. They showed significant reduction in levels of 5-HIAA (70.3 +/- 25.4 pmol/ml). HVA (128.2 +/- 58.3 pmol/ml), and MOPEG (27.7 +/- 7.4 pmol/ml), indicating reduced central metabolism in all three monoamine pathways. The concentrations, in particular that of MOPEG, were inversely correlated with depressive symptoms reported on the MMPI scale 2 ('depression'), which conforms with current concepts on the pathogenesis of depression.