Clinical and secretory data were analysed with respect to the recurrence rate for 685 patients treated with either selective gastric vagotomy (SGV) or parietal cell vagotomy (PCV) for duodenal ulcer disease. The duration of ulcer history before surgery was of no importance for the recurrence risk. Men with recurrence after SGV were significantly younger than men without recurrence, but no difference was found for women with SGV or for men and women with PCV. The recurrence rate was not higher for hypersecretors (pentagastrin-stimulated peak acid output (PAOpg) greater than 45 mmol/h) than for patients with lower PAOpg. Resting, basal, and stimulated secretion 3 months after surgery were higher for the patients with recurrence than for the patients without, but only a few of the secretion values were significantly different. A higher recurrence rate was found for the patients with the lowest initial acid reduction, and this trend was more pronounced in the PCV group. With regard to the change in gastric secretion during the first year after vagotomy a significant rise was seen for the PCV patients who developed recurrence in spite of initial reduction of more than 60%. For all SGV patients and the PCV patients with an initial reduction on the average or less, the change in secretion capacity had no influence on the recurrence rate. The findings are in accordance with reports about anatomical limitations for a sufficient PCV in about 20% of the patients.