The symptoms of functional dyspepsia are still unexplained. To evaluate the possible role of abnormal visceral perception, we studied the symptomatic responses and the pressure variations during progressive gastric distension in 10 female healthy control subjects (mean age 33.6 years) and in 10 female patients with functional dyspepsia (mean age 35.2 years). A rubber balloon was positioned 4 cm below the lower esophageal sphincter (LES) and inflated with progressively larger volumes of air by steps of 50 ml; pressures at the gastric fundus and at the LES were continuously recorded by perfused manometric catheters. Each subject was studied on two separate occasions after randomized double-blind administration of either placebo or 20 mg of domperidone. Symptomatic responses and the manometric data were analyzed at the time of the initial recognition of distension (bloating step) and at the time of reporting pain or up to a maximum of 700 ml of balloon inflation (pain or 700-ml step). On placebo, the volumes of gastric distension were more than two times lower in patients than in control subjects at the bloating step (185±32 ml vs 470±40 ml,P=0.001) and at the pain or 700-ml step (265±54 ml vs 600±34 ml,P<0.005), while="" the="" pressure="" gradients="" (pressure="" at="" inflation="" steps="" minus="" baseline="" pressure="" before="" beginning="" inflation)="" were="" not="" statistically="" different="" between="" the="" two="" groups.="" on="" domperidone,="" the="" volumes="" at="" each="" of="" the="" two="" steps="" did="" not="" change="" in="" comparison="" to="" results="" on="" placebo="" except="" in="" healthy="" controls="" at="" the="" bloating="" step="" (470±40="" ml="" on="" placebo="" vs="" 355±35="" ml="" on="">P<0.001); however,="" there="" was="" a="" trend="" for="" pressure="" gradients="" to="" increase="" on="" domperidone="" in="" comparison="" to="" results="" on="" placebo.="" we="" conclude="" that="" patients="" with="" functional="" dyspepsia="" have="" a="" lower="" threshold="" both="" to="" the="" initial="" symptomatic="" recognition="" and="" to="" perception="" of="" pain="" during="" gastric="" distension="" and="" that="" domperidone="" might="" have="" an="" effect="" on="" the="" threshold="" of="" these="" conscious="" visceral="" sensations.="" this="" increased="" visceral="" perception="" may="" alone="" or="" with="" other="" abnormalities="" of="" the="" gastroduodenal="" tract="" explain="" the="" symptoms="" of="" functional="">