The efficacy and acceptability of classical bismuth triple therapy may be limited by poor patient compliance and adverse effects. It is widely agreed that improved, simpler, and reliable therapies are needed to cure Helicobacter pylori infection and foster patient compliance. We evaluated the efficacy and side effects of a Bazzoli triple therapy substituting lansoprazole for omeprazole for H. pylori infection in active peptic ulcer in Korea (30 mg of lansoprazole, 250 mg of clarithromycin, and 400 mg of metronidazole, all twice daily). H. pylori status was evaluated by rapid urease test, histology, and culture at entry and four or more weeks after ending antimicrobial therapy. Fifty-eight patients (mean age: 43 years) with gastric (N = 30) or duodenal ulcer (N = 28) and H. pylori infection were studied. H. pylori was cured in 47 (81%, 95% CI = 69-90%). Mild side effects, including vomiting, diarrhea, and itching, were observed in four patients (7%). Compliance averaged 95%. Fifty-five ulcers (95%) were healed. Pretreatment pylorobulbar deformity was observed in 49 patients (85%), and in 43 (88%) the deformity disappeared after treatment. Pretreatment metronidazole and clarithromycin resistance was observed in 87% and 2% of patients, respectively. The cure rate of H. pylori infection was significantly higher in patients >50 years of age than those <50. Treatment with low-dose one-week lansoprazole, clarithromycin, and metronidazole resulted in a relatively low cure rate, but was well tolerated. Studies to define the optimal duration, dose, and dosing interval of this combination therapy in Korea are needed.