AIM:To evaluate the association of pre-treatment Helicobacterpylori (H.pylori) density with bacterial eradication and ulcerhealing rates in patients with active duodenal ulcer.METHODS:One hundred and four consecutive duodenalulcer outpatients with H.pylori infection ascertained bygastric histopathology and ~(13)C-urea breath test (UBT) wereenrolled in this study.H.pylori density was gradedhistologically according to the Sydney system (normal,mild,moderate,and marked).In each patient,lansoprazole (30mg b.i.d.),clarithromycin (500 mg b.i.d.) and amoxicillin (1g b.i.d.) were used for 1 week,then 30 mg lansoprazoleonce daily was continued for an additional 3 weeks.Follow-up endoscopy was performed at 4 weeks after completionof the therapy,and UBT was done at 4 and 8 weeks aftercompletion of the therapy.RESULTS:The H.pylori eradication rates were 88.9%/100.0%,94.3%/100.0%,and 69.7%/85.2%;and theulcer healing rates were 88.9%/100.0%,94.3%/100.0%,and 63.6%/77.8% (intention-to-treat/per protocol analysis)in the mild,moderate,and marked H.pyloridensity groups,respectively.The association of pretreatment H.pylori densitywith the eradication rate and ulcer healing rate was bothstatistically significant (P=0.013/0.006 and 0.002/<0.001,respectively;using results of intention-to-treat/per protocolanalysis).CONCLUSION:Intragastric bacterial load may affect boththe outcome of eradication treatment and ulcer healing inpatients with active duodenal ulcer disease. AIM: To evaluate the association of pre-treatment Helicobacter pylori (H. pylori) density with bacterial eradication and ulcer healing rates in patients with active duodenal ulcer. METHODS: One hundred and four consecutive duodenal ulcer outpatients with H. pylori infection ascertained by gastric histopathology and ~ ( 13) C-urea breath test (UBT) wereenrolled in this study. H. pylori density was graded histologically according to the Sydney system (normal, mild, moderate, and marked) .In each patient, lansoprazole (30 mg bid), clarithromycin mg bid) and amoxicillin (1 g bid) were used for 1 week, then 30 mg lansoprazoleonce daily was continued for an additional 3 weeks. Focus-up endoscopy was performed at 4 weeks after completion of the therapy, and UBT was done at 4 and 8 weeks aftercompletion of the therapy .RESULTS: The H.pylori eradication rates were 88.9% / 100.0%, 94.3% / 100.0%, and 69.7% / 85.2%; and the ulcer healing rates were 88.9% / 100.0%, 94.3% / 100.0% , and 63.6% / 77.8% (intention-to-treat / per protoc ol analysis) in the mild, moderate, and marked H. pyloridensity groups, respectively. The association of pretreatment H. pylori density with the eradication rate and ulcer healing rate was both statistically significant (P = 0.013 / 0.006 and 0.002 / <0.001, respectively; using results of intention-to-treat / per protocolanalysis) .CONCLUSION: Intragastric bacterial load may affect both the outcome of eradication treatment and ulcer healing in patients with active duodenal ulcer disease.