From 1 to 5% of patients can be expected to develop recurrent ulceration following current surgical therapy for peptic ulcer disease. The development of recurrent ulcer frequently reflects an inadequacy of the initial procedure. The nature of the inadequacy is often difficult to delineate because of alterations in anatomy and physiology and the lack of accurate diagnostic procedures. Incomplete vagotomy and inadequate gastric resection account for the vast majority of surgical deficiencies. Gastrinoma, retained gastric antrum, and hyperparathyroidism are the most frequently encountered endocrine causes. A thorough evaluation must include gastrointestinal X-rays, fiberoptic endoscopy, multiple serum calcium and gastrin determinations, and provocative testing. Medical management of recurrent ulcer fails in the vast majority of cases. Reoperation is successful in about 70% of cases and has a mortality rate of 4%. Recurrent ulcer after simple gastroenterostomy is best treated by gastric resection or vagotomy and resection. After initial adequate gastric resection, vagotomy alone usually suffices. Antrectomy and, if necessary, re-vagotomy should be done for recurrent ulcer after vagotomy and drainage. Re-vagotomy alone is usually effective therapy for recurrent ulcer after initial vagotomy and resection. Non-acid reducing operations should not be done, as they result in high mortality and high second recurrence rates.