The recurrent ulcer rates in a prespective randomised trial amounted to 26% and 14%, 5 1/2 t0 8 years after highly selective vagotomy without drainage (HSV) and selective vagotomy with pyloroplasty (SV). Long duration of symptoms before HSV increased the risk of recurrence. High preoperative maximum acid secretion increased the risk of recurrence after SV Furthermore, long duration of symptoms and slow postoperative gastric emptying possibly increased the risk of recurrence after SV. Imcomplete vagotomy as expressed by the quantitative acid response to insulin was also considered to be of significance for the risk of recurrence in the present study.