Gastrointestinal tract involvement in Langerhans'cell histiocytosis (LCH) is unusual. It is most often observed in children, is usually asymptomatic, diagnosed at post mortem examination and associated with a disseminated disease. We report 2 cases of LCH large bowel involvement occuring in a 50-year- old man and in a 71-year-old woman, who presented with digestive symptoms. Histiocytic proliferation with reniform nuclei was demonstrated in colonic biopsies it was located in the lamina propria, and dissociating the mucosa glands. Immunohistochemical study revealed a strong positivity of these cells with anti-CD1a and anti-PS100 antibodies. Ultrastructural study performed in one case showed large cells with reniform and indented nuclei, numerous tubuloreticular structures and Birbeck granules. Digestive localization of LCH is exceptional in adult, and may be underestimated.