Superficial erosions of the esophagus are by no means an uncommon accompaniment of the stagnation of food and secretions. From the irritation they produce, spastic stenosis may occur, thus constituting a vicious circle; the spasm of the esophagus increases the stagnation which in turn results in further inflammation and ultimate ulceration. Healing of such ulcers may result in cicatricial contraction and organic stenosis. Ulceration may follow trauma by instrument, foreign body, or corrosive. DIFFERENTIAL DIAGNOSIS OF ULCER OF THE ESOPHAGUS _Simple ulcer_ requires the exclusion of lues, tuberculosis, epithelioma, endothelioma, sarcoma, and actinomycosis. Simple ulcer of the esophagus is usually associated with stenosis, spastic or organic. _Luetic ulcers_ commonly show a surrounding inflammatory areola, and they usually have thickened elevated edges, generally free from granulation tissue, with a pasty center not bleeding readily when sponged. The Wassermann reaction may contribute to the diagnosis; but if negative, a thorough and prolonged test with mercury is imperative. It must be remembered that a person with lues may have a simple, mixed, or malignant ulceration of the esophagus, or the three lesions may even be combined. It may be in some cases possible to demonstrate the treponema pallidum in scrapings taken from the ulcer. The single _tuberculous ulcer_ is usually pale, superficial, and granular in base. If it is a continuation from more extensive extra-esophageal tuberculous ulceration, pale cauliflower granulations may be present. Slight cicatrices may be seen. Tuberculosis in other organs can almost always be demonstrated by roentgenographic, physical, or laboratory studies. Tuberculin tests and animal injection with an emulsion of a specimen of tissue may be required. The specimen must be taken very superficially to avoid risk of perforation. _Sarcomatous ulcers_ do not differ materially in appearance from those of carcinoma, but they are much more rare. _Carcinomatous ulcer_ is usually characterized by the very vascular bright red zone, raised edges, fungations, granulation tissue that bleeds freely on the lightest touch, and above all, it is almost invariably situated on an infiltrated base which communicates a feeling of hardness to the pressure of sponges or the esophagoscope itself. A scar may be from the healing of an ulcer from stasis, or one of specific or precancerous character. It may be a cancerous process developing on the site of a scar, so that the presence of scar tissue does not absolutely negative malignancy. As a rule, however, scars are absent in cancer of the esophagus. The firm and sometimes prominent ridge of the crossing of the left bronchus must not be mistaken for infiltration, and the esophagoscopist must be familiar with the normal rigidity of the cricopharyngeus.