We have measured the rate of gastric emptying of solid and liquid meals by an external scanning technique and have studied pyloric reflux by a radiological technique. Investigations were performed in patients with uncomplicated hiatal hernia, patients with uncomplicated duodenal ulcer and normal controls. There was a significant delay in the emptying of both solid and liquid meals in the patients with hiatal hernia compared with both the duodenal ulcer patients (solid meals P < 0·01, liquid meals P < 0·025) and with normal controls (solid meals P < 0·05, liquid meals P < 0·001). Duodenogastric reflux was observed in 35 per cent of hiatal hernia patients compared with 24 per cent of duodenal ulcer patients and no incidence in the controls.