Abstract Ulceration of the small intestine is an uncommon lesion of multifactorial origin. The most important factor responsible for the reported increased incidence is the ingestion of enteric-coated potassium chloride. It is desirable that potassium supplements be given in another form, for example as a slow-release preparation. Other drugs which may play a part in the aetiology include corticosteroids and phenylbutazone. Diagnosis is difficult and ulceration is usually only demonstrated after one of the complications (obstruction, perforation, or haemorrhage) has occurred. It is imperative that a full drug-taking history is obtained. Laboratory tests are not helpful in diagnosis, but where radiological studies are carried out they often contribute useful information. If the symptoms of such an ulcer are severe enough to warrant laparotomy, then the treatment of choice is excision of the affected segment followed by end-to-end anastomosis.