This study investigated the assessment of visceral perception and gastric tone using insufflation during endoscopy. The intragastric pressure was measured during insufflation in 16 patients with gastro-oesophageal reflux disease, 25 patients with functional dyspepsia and 24 normal controls, using a pressure transducer inserted through the forceps aperture until gastric symptoms appeared. The intragastric pressure at the visceral perception threshold, the time to threshold and the time-pressure curve gradient were measured. The visceral perception threshold was significantly reduced in the functional dyspepsia group compared with the normal controls. Balloons were also inserted into the duodenal bulbs of 10 normal controls to investigate the effect of efflux of air into the duodenum; the measured parameters were not influenced by inflation and deflation. These results suggest that it is possible to assess visceral perception and gastric tone by measuring changes in intragastric pressure, using gastric stimulation by insufflation during endoscopy.