OBJECTIVE: There are no studies on the prevalence of celiac disease (CD) in either Brazil or, as far as we know, South America. The aim of this study was to determine the prevalence of CD in healthy blood donors in the city of Brasilia, Brazil. METHODS: Sera were obtained, independently of age and gender, from an unselected group of 2045 blood donors attending the Hematological Center of Brasilia. An IgG antigliadin antibody (AGA) test was used as a first-level screening step, followed by IgA-AGA test, serum IgA antiendomysium (EMA), and total serum IgA determination performed in all sera showing abnormally high IgG-AGA results. Jejunal biopsy was suggested for all subjects showing at least one of the following: IgA-EMA positivity; IgG-AGA and IgA-AGA positivity; IgG-AGA positivity and selective IgA deficiency. AGA was determined by an enzyme-linked immunosorbent assay (ELISA) technique and IgA-EMA was ascertained by indirect immunofluorescence on cryostat sections of monkey esophagus. Jejunal mucosa samples were obtained with a Watson capsule. RESULTS: Sixty-two (3.03%) blood donors had IgG-AGA above the cut-off values. Fifty-eight individuals showed isolated high values of IgG-AGA, whereas four had simultaneously increased IgG and IgA-AGA. Three patients had positive IgA-EMA test (one with both IgG- and IgA-AGA and two with only IgG-AGA) and underwent jejunal biopsies that disclosed complete villous atrophy associated with an increased number of intraepithelial lymphocytes and hypertrophic criptae. In this study group, the prevalence of biopsy-proven celiac disease was 1.47 +/- 1.66 in 1000 subjects. CONCLUSIONS: We found a prevalence of undiagnosed CD of 1:681 among apparently healthy blood donors. These preliminary results support the view that CD is not a rare disease in Brazil.