Background and Aims: We recently found a close temporal correlation between the onset of heartburn induced by acid infusion into the esophagus (positive Bernstein test) and a sustained esophageal contraction (SEC). A number of investigators have observed that repeated acid infusions induce stronger symptoms (symptom hypersensitivity). The goal of our study was to determine if symptoms hypersensitivity is associated with esophageal contractile hypersensitivity. Methods: Subjects with chronic heartburn symptom underwent simultaneous pressure and ultrasound imaging of the esophagus. Normal saline and 0.1 N HCl was sequentially infused into the esophagus and subjects scored heartburn symptom on a scale of 1-10. Saline and HCl infusions were repeated in 10 subjects with a positive Bernstein test. Data Analysis: Esophageal contraction amplitude, contraction duration and thickness of the muscularis propria (using a computerized method) were measured during the entire period of recording. Results: Acid infusion induced heartburn. Esophageal contractions were higher amplitudes, (pressure 114.2 ± 7.0%), and longer duration (116.8 ± 4.4%) during acid as compared to saline period. The average muscle thickness during acid was greater than during saline period (107.0 ± 2.0%). SECs were identified during acid infusion period. Second acid infusion induced heartburn with shorter latency (93.0 ± 15.0 s vs. 317.0 ± 43.0 s) and stronger severity (8.5 ± 0.5 vs 5.3 ± 0.8) than the first acid infusion. Contractions amplitudes (140.2 ± 13.0%), average muscle thickness (118.0 ± 3.3%) and contraction duration (148.5 ± 5.6% vs 116.8 ± 4.4%) were higher during 2^nd acid infusion than 1^st. In addition, numbers of SECs were greater during 2^nd as compared to 1^st acid infusion (31 in 8 subjects vs 11 in 6 subjects). Conclusion: our data show that acid infusion in to the esophagus induces esophageal hypersensitivity and that there is a close temporal correlation between symptom hypersensitivity and contractility hypersensitivity.