Objective: This study examined the effect of administration with food on the ability of ranitidine bismuth citrate to suppress and eradicate Helicobacter pylori in 41 infected volunteers. Results: After a 7-day course of treatment with ranitidine bismuth citrate (400 mg b.i.d.), 90% (18/20) of subjects who received the drug with food compared with 55% (11/20) of subjects who received the drug without food tested H. pylori-negative in a C-13-urea breath test (p = 0.031), Follow-up C-13-urea breath tests performed at least 3 months after therapy showed that H. pylori was eradicated in 14% (2/14) of subjects who received ranitidine bismuth citrate with food compared with 0% (0/18) of subjects who received ranitidine bismuth citrate without food (p = 0.183), The incidence of potentially drug-related adverse events was similar regardless of whether subjects received ranitidine bismuth citrate with or without food. Headache was the most common potentially drug-related adverse event. Conclusions: These data demonstrate that administration of ranitidine bismuth citrate with food compared with without food significantly improves the suppression of H. pylori in infected volunteers.