Patients who cannot secrete ABO and Lewis blood group antigens into body fluids, an ability controlled by a single gene on chromosome 19, are known to be at increased risk of certain autoimmune diseases associated with human leucocyte antigen (HLA) markers. This study investigated the possibility of an association with coeliac disease using red cell Lewis (Le) blood group phenotype to infer secretor status. Among 73 patients with coeliac disease who had Le a or b antigen, 48% were non-secretors (Le a + b-) compared with 27% of 137 blood donors (p = 0.004: odds ratio 2.49, 95% confidence intervals 1.37 to 4.51) and 26% of 62 medical and nursing staff controls (p = 0.014: odds ratio 2.65, 95% confidence intervals 1.27 to 5.50). Clinical characteristics did not differ between secretors and non-secretors with coeliac disease. Thus, the non-secretor state is significantly associated with coeliac disease, suggesting that genes on chromosome 19 may directly or indirectly participate in conferring susceptibility.