Serologic testing is generally accepted as a valid noninvasive screening method for the detection of a Helicobacter pylori infection. To validate serology as an appropriate screening test for H pylori infection in symptom-free subjects, a recent-generation enzyme-linked immunosorbent assay for the detection of H pylori-specific IgG was performed in a large series of asymptomatic women. Blood samples for H pylori serology were taken from 542 apparently healthy women (aged 20 to 40 years) during prenatal screening. In this group, 120 (22.1%) had a positive titer for H pylori. We observed a significantly higher overall prevalence of H pylori seropositivity in nonwhites (62.3%) when compared with Belgian-born whites (17.8%). In both groups there was a significant increase in seropositivity with increasing age. To investigate the correlation between a positive enzyme-linked immunosorbent assay and the actual presence of an active H pylori infection, carbon 13-labeled urea breath tests were performed in 85 seropositive and in 65 randomly selected seronegative subjects. These breath tests were positive in 82 (96.5%) of 85 seropositive and in none of the seronegative subjects, reflecting an actual presence of H pylori in the gastric mucosa of the seropositive women. We conclude that in our population of H pylori-seropositive subjects positive serologic findings correlates extremely well with an active infection with this bacterium. However, because all subjects who were investigated were actually symptom-free, it still should be determined whether these patients should undergo upper gastrointestinal endoscopy and/or be treated with an eradication therapy against H pylori. Further long-term follow-up studies will be required to answer this question.