The role of probiotics in Helicobacter pylori therapy remains unclear. Lactobacilli can be shown to inhibit H pylori in vitro. Some strains of Lactobacilli may exert specific antimicrobial effects. There is no strong evidence of a benefit on eradication rate when probiotics are added to a regimen. Despite promising results obtained using compounds of L reuteri and S boulardii, high-quality trials are needed to define the role of probiotics as adjuvant therapy. Variables that remain to be studied with L reuteri, currently the most promising strain, include dosage, frequency of administration, administration in relation to meals, and duration of therapy.