UNLABELLED: Patients with non ulcer dyspepsia (NUD) and lowered mechano sensitivity thresholds in stomach may have lowered mechano sensitivity thresholds in oesophagus also. The aim was to check this hypothesis. METHODS: 39 patients with NUD (11 men and 24 women, mean age 57 years, SEM 3.72, range 17-86) and 20 controls (10 men, 10 women, mean age 49.3 years, SEM 3.72, range 31-66) were studied. Organis diseases were discarded. Gastric mechano sensitivity was studied with a latex balloon of low compliance, 8 cm length, connected to a manometer. Balloon was inflated "in ramp" at 10 ml/sec, and "first sensation", discomfort", and "pain" were registered. At 900 ml inflation was stopped if pain was not evoked. Oesophageal mechano sensitivity was studied with another latex balloon of low compliance which, after inflated with 15 ml. of air, was 3.5 cm. in diameter. Esophageal balloon was inflated "in ramp" (1 ml/sec) up 15 ml. and deflated in 2 cm step from 36 to 22 cm from SDA. Inflation was stopped when symptoms (pain or discomfort were evoked. Oesophageal acid perfusion test was performed. RESULTS: 83.4% of controls completed up 700 ml. of gastric distension vs. 35.9% of patients with NUD (p > 0.001). No significative differences in intra-balloon pressure slope were observed between both groups. 79.2% of NUD patients had chest pain with oesophageal ballon distension = < 7 ml. vs. 5% in controls (p > 0.001). Mean volumes were 7.03 ml. (NUD) and 11.9% (controls) (p = 0.001), 63% of dyspeptic patients with lowered gastric sensitivity thresholds (< 700 ml) had oesophagic symptoms with inflation volumes = < 7 ml. There was a positive correlation in stomach and oesophageal mechano sensitivities variations (r = 0.75, +/- 0.58, p > 0.01). When analyzed with that results, oesophageal acid perfusion test showed 38.5% of "mixed sensitivities" (both mechano- and chemo-), 30.7% of "mechano sensorials" (negative acid test, positive balloon test), and 10.3% of :chemo sensorials" (positive acid test only). In 20.5% both tests were normal at the moment they were done. These results agreed with our previous experiences in oesophagus. CONCLUSIONS: It was concluded that a significative proportion of NUD patients had lowered thresholds for mechano stimulation of stomach and oesophagus at the time that both tests were done. Such alterations support the hypothesis that a more general mechano-sensitivity alteration is present in patients with NUD.