Three hundred and six (94%) of all consecutive patients with prepyloric or duodenal ulcer disease undergoing highly selective vagotomy at a District General Hospital were followed up after 1 to 10 completed years of observation. The 5− and 10-year cumulative recurrence rates were 11.6% and 16.8%, respectively. These figures were not related to age, sex, duration of ulcer disease, or preoperative peak acid output. Prepyloric ulcers had a significantly higher recurrence rate than duodenal ulcers during the first 5 years but this difference was eliminated at 10 years. The recurrence rates varied highly significantly between different surgeons. The 5-year recurrence rate in patients operated during the first 5-year period amounted to 13.4% and was steadily increasing. A corresponding figure for those operated during the second 5-year period was 5.3% and remained constant after 3 years of observation. This difference might reflect an improved surgical technique initiated by repeated evaluation of the clinical results.