In the present work we study the association between chronic active gastritis (CAG), atypical regeneration and dysplasia and gastric Helicobacter pylori (HP) infection. We study two groups of endoscopic biopsies. Regenerative changes and dysplasia were evaluated according to Gandur-Maymneh et al. classification which was simplified in typical and atypical regeneration, and mild and severe dysplasia. The group I included 94 patients with CAG, 9 with chronic non active gastritis (CNAG) and 2 with normal gastric mucosa. CAG was graded according to activity in; severe 28 patients; moderate 54 patients and; mild 12 patients. HP association in these cases was 100%, 77% and 25%. In cases of CNAG HP was present in 22%, there were not HP in normal gastric mucosa. There were atypical regeneration in 25% of moderate CAG and in 42% of severe CAG. Mild dysplasia was present in 7.5 and 25% in cases of moderate and severe CAG. Two biopsies showed severe dysplasia. In addition, intestinal metaplasia was found in 15% of CAG, the metaplasia was present in 25% of cases with CAG and atypical regeneration; in 54% of cases with mild dysplasia and; in 100% on cases with severe dysplasia. The group II included 9 cases of gastric cancer of intestinal type, 7 cases of diffuse type, and 4 cases of mixed type. In all these cases there was viewed CAG associated to HP infection in non-neoplastic mucosa. In 75% of cases there were showed atypical regeneration and 60% presented some type of dysplasia. There was transition between atypical regeneration and dysplasia in 6 cases of intestinal gastric cancer and in 3 cases of mixed type. We found relationship between the intensity of CAG and HP colonization, and the association with atypical regeneration and dysplasia.