In a series of measurements of liquid-phase gastric emptying using a radionuclide marker on 35 subjects, five were identified in whom the proximal stomach and antrum were clearly distinguishable. Three of these subjects were normal controls and two suffered from systemic sclerosis. In the three normal subjects, analysis of the movement of the liquid showed the expected movement from fundus to antrum and thence through the pylorus. In the two patients with systemic sclerosis, there was, in contrast, evidence of mass retropulsion of the contents of the antrum into the fundus. In such cases, the measurement of stomach emptying based on the assumption of a single-compartment system in likely to be misleading.