Serum IgA antigliadin antibodies (IgAAGA) assay, cellobiose/mannitol sugar permeability test (ST), and carotenemia were evaluated prospectively as diagnostic tests in 60 consecutive adult patients with suspected celiac disease (CD). CD was confirmed histologically in 26 patients. IgAAGA, ST, and carotenemia had a sensitivity of 65.4%, 96.2%, and 76.9%, a specificity of 97.1%, 73.5%, and 70.6%, and positive likelihood ratio of 22.2, 3.6, and 2.6, respectively. Multivariate logistic regression showed that IgAAGA and ST had a sensitivity and specificity of 96.2% and 70.6% and a positive likelihood ratio of 47.3 if both were positive. Assuming a prevalence of CD of 1:2000 in the general population, for every 89 positive IgAAGA and 549 altered ST there would be one celiac patient, whereas, if both tests were positive, the patient was certain to have CD. We conclude that, of the tests studied, IgAAGA and ST are respectively the most specific and the most sensitive and that, used together, they can diagnose CD.