The presence of Helicobacter pylori in saliva specimens collected from infected children examined before and after specific therapy and from a non-infected pediatric population was detected by indirect immunofluorescence assay (IIF) using a specific monoclonal antibody. Among the 25 children with H. pylori-negative antral biopsies, 4 had in their salivas bacterial cells similar to H. pylori, but a retrospectively performed serologic test showed a positive response. No false-positive reaction was observed among non-infected and seronegative children. The observation of bacterial cells with H. pylori morphology in saliva by IIF was consistent with the presence of this bacterium in antral biopsies. A person-to-person transmission of H. pylori by saliva thus appeared to be possible.