It has been previously observed that in dyspeptic patients with "hunger pain", that is, with pain suggestive of the presence of peptic ulcer, only 12% had an endoscopically demonstrated ulcer, the remaining 88% showing absence of important macroscopically detectable lesions (idiopathic dyspepsia). In order to investigate the possibility of a relationship between "hunger pain" and some alteration in gastroduodenal motility, the gastric emptying rates of patients presenting idiopathic dyspepsia with and without "hunger pain" were compared with those of normal control subjects. The study was conducted in 40 patients presenting idiopathic dyspepsia, 20 with and 20 without "hunger pain", and 30 voluntary apparently normal control subjects. The patients and the controls ingested, with a standard breakfast, a gelatine capsule containing 10 radioopaque polyurethane markers, and the gastric emptying of the markers was evaluated taking 3 x-ray films of the abdomen at 1.5, 3.0 and 4.5 hours after the breakfast. The gastric emptying rates of the markers were significantly higher in the patients with "hunger pain", and significantly lower in the patients without "hunger pain", than in the normal control subjects. In idiopathic dyspepsia with and without "hunger pain" there are, respectively, abnormally increased and abnormally decreased gastric emptying rates of undigestible solid markers. Our findings could help to better understand the pathogenesis of those different types of dyspepsia and, consequently, to improve their treatment.