The effect of an effortful swallow on the healthy adult esophagus was investigated using concurrent oral and esophageal manometry (water perfusion system) on ten normal adults (5 males and 5 females, 20-35 years old) while swallowing 5-ml boluses of water. The effects of gender, swallow condition (effortful versus noneffortful swallows), and sensor site within the oral cavity, esophageal body, and lower esophageal sphincter (LES) were examined relative to amplitude, duration, and velocity of esophageal body contractions, LES residual pressure, and LES relaxation duration. The results of this study provide novel evidence that an effortful oropharyngeal swallow has an effect on the esophageal phase of swallowing. Specifically, effortful swallowing resulted in significantly increased peristaltic amplitudes within the distal smooth muscle region of the esophagus, without affecting the more proximal regions containing striated muscle fibers. The findings pertaining to the LES are inconclusive and require further exploration using methods that permit more reliable measurements of LES function. The results of this study hold tremendous clinical potential for esophageal disorders that result in abnormally low peristaltic pressures in the distal esophageal body, such as achalasia, scleroderma, and ineffective esophageal motility. However, additional studies are necessary to both replicate and extend the present findings, preferably using a solid-state manometric system in conjunction with bolus flow testing on both normal and disordered populations, to fully characterize the effects of an effortful swallow on the esophagus.