Aim.Infected parents, especially infected mothers, may play a key role in transmission ofHelicobacter pyloriwithin the family. The aim of this population-based study was to determine the role of parental infection status in transmission ofH. pylorito the child by taking into consideration the infection status of both parents simultaneously.Methods.Study subjects were a sample of preschool children in the city of Ulm, located in Southern Germany, who were screened for school fitness between January and July, 1998. The infection status of the children was determined by the13C-urea breath test (UBT). Parental infection status was determined by measurement of specificH. pyloriIgG antibodies in saliva using a modified immunoassay (MileniaH. pyloriIgG; DPC, Biermann, Germany). The parents provided additional information through a standardized questionnaire.Results.We included 305 children ages 5 to 7 years (mean age, 5.8 years) and their parents in the analysis. Prevalence ofH. pyloriinfection in children by means of UBT was 10.2% [95% confidence interval (CI) 7.0–14.1%]. The prevalence of infection was 5.1% if the mother showed no salivary antibody response againstH. pyloriand 17.3% if she did. Prevalence of infection in children was 6.8% if the father showed no salivary antibody response and 19.1% if he did. After adjustment for potential confounders (including infection of the spouse), the odds ratio forH. pyloriinfection of the child was 3.9 (95% CI 1.4 to 10.6) when the mother was saliva-positive and 2.0 (95% CI 0.8 to 5.3) when the father was saliva-positive.Conclusion.This study strengthens previous evidence that in the population studied infected parents, in particular mothers may play a key role in transmission ofH. pylorito the child.