Circadian rhythmic variation has been documented in gastric, small bowel and colonic motility. Morning and evening studies of esophageal motility were performed to assess whether similar rhythmicity exists in esophageal function. Fifteen healthy male subjects were studied twice on separate study days. Esophageal manometry was performed either at 10 AM or 10 PM after a standardized meal given 10 h prior to each study. Lower esophageal sphincter pressures, distal esophageal contractile amplitudes, distal esophageal contractile durations, and the velocity of propagation of peristaltic waves in the proximal and distal esophagus were measured. No significant differences were detected in esophageal function between day and night studies. These findings suggest either 1) nocturnal slowing of gastrointestinal motility is not a generalized characteristic of the entire GI tract, or 2) a two time-point study is not adequate to detect a true circadian rhythm in esophageal motor function.