Midazolam, a water-soluble benzodiazepine, has recently been introduced and found to be beneficial for sedation in upper GI endoscopy. Whereas it has been proven that diazepam does not have any effect on sphincter of Oddi (SO) motility in humans, no respective data exist on midazolam. On evaluation of the possible effects of midazolam on SO motility recording by means of endoscopic manometry, we found that midazolam had no effect on basal pressure (24.2 +/- 12.59 mm Hg before and 23.85 +/- 12.63 mm Hg after midazolam, p = 0.55), amplitude (39.75 +/- 22.62 versus 44.55 +/- 27.15, p = 0.097), duration (4.9 +/- 1.8 sec versus 5.05 +/- 1.7 sec, p = 0.614), and frequency of SO contractions (7.75 +/- 1.68 waves/min versus 7.15 +/- 1.92 waves/min, p = 0.083). These results suggest that in patients with normal manometric findings midazolam does not interfere with SO recording.