To assess the efficacy and safety of ranitidine bismuth citrate plus clarithromycin given for 1 wk in Brazilian patients with peptic ulcer. One hundred and twenty patients with peptic ulcer were randomized in two treatment groups: (1) 1-wk regimen consisting of ranitidine bismuth citrate 400 mg b.i.d. with clarithromycin 500 mg b.i.d. or (2) 2-wk regimen of the same treatment. Eradication of the infection was considered when both the histologic examination and the urease test were negative for the infection 3 mo after treatment. By intention to treat analysis, Helicobacter pylori (H pylori) was eradicated in 73% and 76% of patients, respectively treated for 1 or 2 wk (P>0.05). By per protocol analysis, the eradication rates were 80% and 83%, respectively, in patients treated for 1 or 2 wk (P>0.05). Nine patients (8.2%) reported minor side effects. One-week therapy with ranitidine bismuth citrate and clarithromycin is safe, well tolerated and effective for treatment of H pylori infection, and appears to be comparable to the 2-wk regimen in terms of efficacy.113566-9