The histopathological study of the digestive mucosae has a great diagnostic value. It appreciates lymphoid tissue; it may suggest AIDS when it discloses rare inflammatory or tumoral lesions; it may disclose an infectious and/or Kaposi sarcoma lesion which may be the first manifestation of AIDS in a seropositive LAV patient or may be an additional lesion in a patient known to have AIDS. The autopsies have shown the spread of the extension and the evolution of these lesions. The discussion of the histopathological lesions must always include the extra-digestive localisations as well as the "non opportunistic" associated infections.