Infectious oesophagitis is the most frequent of digestive tract diseases occurring in patients with AIDS. It is diagnosed by endoscopy which permits brushing and biopsy of mucosal lesions for cytological, histological and microbiological examinations. In 40 to 50 percent of HIV positive patients, Candida is responsible for oesophagitis which is often asymptomatic and almost regularly associated with oral candidiasis. Brushing is preferable to biopsy to confirm a diagnosis which is frequently obvious at endoscopy. The prevalence of CMV and HSV oesophagitis has perhaps been underestimated. Diagnosis rests on the finding of intranuclear inclusions, usually in endothelial cells of the chorion for CMV and in epithelial cells for HSV. The demonstration of viral antigens by immunoperoxidase staining is useful in difficult cases, as is viral culture. Antiviral agents (gancyclovir against CMV, acyclovir against HSV) are usually effective. Co-infection with both Candida and a virus is not uncommon. The other pathogens, such as bacteria or mycobacteria, are exceptional. The authors suggest a therapeutic strategy taking into account epidemiological and clinical data.