It's a prospective study leaded between September 1997 and july 1999 (23 months ) in 75 patients with duodenal ulcer and positif for Helicobacter pylori. All patients had a first endoscopy with antral, fundic and duodenal biopsies, followed one month later by a second control fibroscopy with biopsies of the same sites. A total of 420 biopsies was realised. Chronic gastritis was evaluated according to sydney system. Patients was divided by randomisation in 4 groups. Every group was received a different therapeutic association. The results was conform to liberation concering activity 80%, intestinal metaplasia 12%. inflammation 100%. Atrophy was observed in 56% of cases, this percentage is variable in literature; chronic gastritis was predominant in antre relatively to fundus (p<0.005). After treatment, a significative fall of Helicobacter pylori and activity and atrophy was established, contrarity to intestinal metaplasia and chronic inflammation witch are persisted. The prevalence of follicular gastritis was 57%. The better rate of ulcer cicatrisation and Helicobacter pylori eradication was respectively of 79% and 66% in group 1 treated by omeprazol, amoxcillin, metronidazol by comparison with the others 3 groups (p<0.005).