To ascertain the effect of gastric emptying on the symptoms of non-ulcer dyspepsia (NUD) patients, we randomly selected 60 NUD patients and, as control, 26 dyspepsia-free volunteers. We measured the gastric emptying time of mixed food (270 kcal), using real-time ultrasonography in two ways. NUD patients were divided randomly into two groups and given domperidone or placebo in a double-blind trial. Of the NUD patients 48% had delayed gastric emptying times and associated epigastric pain, bloating, early satiety, and regurgitation. A prokinetic agent not only improved emptying time but also relieved some of the symptoms of the NUD patients. Real-time ultrasonography proved a useful method for evaluating gastric emptying.