The majority of patients with newly diagnosed coeliac disease have iron deficiency anaemia. Occult gluten enteropathy is common. We looked at blood donor volunteers, unable to donate because they were unexpectedly found to be anaemic, to determine the incidence of coeliac disease and whether this diagnosis is routinely considered. In a 4 month period, 110,973 blood donor volunteers were seen and 1% (1197 women and 183 men) were found to be anaemic. Of 483 anaemic samples selected for testing, 32 out of 483 were positive for IgA anti-endomysial antibodies. Microcytic anaemia was found in all but three of the 32 seropositive cases. Twenty-five out of 32 volunteers agreed to have endoscopic small bowel biopsies and 22 out of 25 (88%) had the typical histological appearances of coeliac disease. Twenty-one out of 22 cases were women. In no case prior to our intervention had these women been investigated for the possibility of coeliac disease. By selecting anaemic subjects for screening, there was an improved detection rate (over 6%) compared with non-anaemic volunteers (0%). There were far more anaemic women in the study population (ratio of anaemic women to anaemic men 5.5:1). We show that, especially in anaemic menstruating women, coeliac disease is unrecognized and under-investigated.