Visceral hypersensitivity may play a role in the pathogenesis of functional chest pain, although the underlying mechanism(s) is unknown. We investigated the effects of theophylline, an adenosine receptor antagonist, on sensory perception and biomechanical properties of esophagus in patients with functional chest pain. Esophageal balloon distention was performed using impedance planimetry in 21 consecutive patients with functional chest pain. Patients found to have a hypersensitive esophagus received intravenous theophylline and balloon distension was repeated. If the hypersensitivity improved, oral theophylline was prescribed for three months as an open label trial. Balloon distension reproduced typical chest pain in 16 (76%) patients at thresholds suggestive of hypersensitivity. After theophylline infusion, pain thresholds increased in 12 (75%) patients. Median threshold pressures for discomfort and pain improved (P < 0.01). Cross-sectional area increased (P < 0.05) and the tension/strain association shifted to the right (P < 0.01). Seven of eight patients reported sustained improvement in pain after oral theophylline. Theophylline may ameliorate chest pain in patients with hypersensitive esophagus, possibly by altering adenosine-mediated nociception.