A prospective study of patients with upper gastrointestinal bleeding admitted to a haematemesis and melaena unit has revealed an incidence of Mallory-Weiss tears of 8% (59 of 762 patients undergoing endoscopy). Prior vomiting was present in 60% and an associated upper gastrointestinal lesion in 44 percent. The majority of patients had a recent ingestion of alcohol and/or analgesics, whilst 34% had chronic heavy alcohol intake. Approximately 50% of patients required no blood transfusion, while 37% had over three units of blood. No patient in the group required surgical intervention, and one patient died because of general debility. This study suggests that the Mallory-Weiss tear accounts for a significant proportion of patients admitted with upper gastrointestinal bleeding, but that the mortality and morbidity are low.