The present study investigated the effect of a model urease-binding polysaccharide in combination with a histamine H₂ receptor antagonist on Helicobacter pylori colonization in vivo. Euthymic hairless mice were treated daily with dextran sulfate via drinking water and/or famotidine via intragastric gavage starting at 1 week postchallenge with a CagA⁺ VacA⁺ (type 1) strain of H. pylori. Treatment of precolonized mice for 2 weeks with dextran sulfate combined with famotidine yielded a group mean bacterial load (per 100 mg of gastric tissue) of log₁₀ 1.04 CFU, which was significantly lower than those of the famotidine (log₁₀ 3.35 CFU, P < 0.01) and dextran sulfate (log₁₀ 2.45 CFU, P < 0.05) monotherapy groups and the infected nontreated group (log₁₀ 3.64 CFU, P < 0.01). Eradication was achieved after 2 weeks of treatment in 50% or more of the test mice using drug combinations (1 or 2 weeks of famotidine plus 2 weeks of dextran sulfate) versus none in the monotherapy and positive control groups. The enhanced activity of the drug combination may be related to the daily pattern of transient acid suppression by famotidine inducing periodic bacterial convergence to superficial mucus sites penetrated by dextran sulfate from the lumen. Increased urease-dextran sulfate avidity was observed in vitro in the presence of famotidine and may partly account for the enhanced activity. With potential utility in abbreviating treatment time and eradication of antibiotic-resistant strains, the use of urease-targeted polysaccharides concurrently with a gastric acid inhibitor warrants consideration as an additional component of the standard multidrug chemotherapy of H. pylori infection.