In order to determine normal ranges for positive and negative titres using a new commercially available second generation serologic ELISA test for the detection of Helicobacter pylori IgG antibodies (Malakit by Biolab, Limal, Belgium) we investigated 560 asymptomatic pregnant women aged 20 to 44. 128 patients (22.9%) had a positive titre for Helicobacter pylori. Although we were able to observe an increase of the number of seropositive subjects with advancing age, a significant increase in titre with age, both for positive and negative titres, could not be demonstrated. Although there was a much higher prevalence of Helicobacter pylori seropositivity in patients with a non-caucasian ethnic background, we did not observe a significant difference in cut-off limit between the different ethnic populations. In all seropositive patients a control serology and 13C-urea breath test were performed 4 to 6 months later. In 124 patients (96.9%) both control examinations were positive. The positivity of the 13C-urea breath test suggests an existent Helicobacter pylori infection in these (symptom-free) women. 13C-urea breath tests were also performed in 100 randomly selected seronegative women and were all negative, as well. Since 13C-urea breath tests were positive in seropositive subjects and negative in seronegative women, we validated the manufacturer's previously established cut-off values, based on only 37 adult patients, in a much larger population.