We report five new patients with coeliac disease and Down syndrome and review the 11 cases previously reported in the literature. In 14 of these 16 patients diarrhoea was the presenting symptom and in 2 failure to thrive in combination with anaemia. The frequency of coeliac disease in children with Down syndrome was calculated as being 43 times greater than in children without Down syndrome. Delay between first symptoms and diagnosis in patients with combined coeliac disease and Down syndrome was 2.5 years, while in the other children with coeliac disease it was only 8 months. This distinctive difference could be caused by an underestimation of the seriousness of gastro-intestinal complaints in patients with Down syndrome. It is stressed that coeliac disease should be strongly considered in all children with Down syndrome and either persistent diarrhoea or failure to thrive.