Collagenous colitis belongs to the group of microscopic colitis. The aetiology and pathogenesis are unknown but different pathogenic hypothesis, autoimmune, infectious, alimentary and medicinal being are advanced, the last one being the most frequent aetiology. The collagenous gastritis is a rare entity and its association with collagenous colitis was exceptionally reported, only six cases being published. We report the seventh case of collagenous gastritis, ileitis and colitis in a 75-year-old woman with chronic diarrhea and important weight loss. This thickened subepithelial collagen band was appeared in an autoimmune injury context with antecedent of Hashimoto's thyroiditis and probably chronic atrophic Biermer's gastritis. The clinical and histological evolution was favourable with budesonide.