['The present study was aimed at assessing the predictive utility of anti-Cag A antibodies in differentiating patients of duodenal ulcer (DU) and non ulcer dyspepsia (NUD) from asymptomatic controls in a developing country.', 'Sera from 120 subjects were tested for antibodies to Cag A using the immunodominant portion of a recombinant 37.5 kDa fusion protein by ELISA, in endoscopically proven cases of DU and NUD and healthy controls.', 'The observed optical density (OD) in DU and NUD patients was 1,947 and 1,960 respectively, which was higher than that observed in controls (p < 0.01), but there was no difference in the anti-Cag A antibody titers between DU and NUD patients.'] Are antibodies to Cag A protein predictive of serious gastroduodenal disease in Indian patients?