This study was performed to evaluate whether the presence of either nasal or oral gastric tubes (GTs) would affect the ability to accomplish transesophageal atrial pacing (TAP). After endotracheal intubation, pacing esophageal stethoscopes were placed and the TAP thresholds were measured in 20 patients. With the PES fixed in position, GTs were inserted and pacing thresholds were remeasured. TAP was accomplished in all patients pre- and postinsertion. The mean +/- SD, range, and median TAP thresholds (mA) were 13.7 +/- 5.8, 7-25, and 12 preinsertion and 13.9 +/- 5.2, 5.5-25, and 13 postinsertion. The preinsertion-postinsertion differences ranged from -6 to 5 mA with a mean of the difference of -0.2 mA (95% confidence interval, -1.61-1.21 mA). No significant difference between the pre- and postinsertion groups was detected by the paired t-test, P = 0.77. In summary, the presence of GTs does not significantly affect TAP thresholds. Attempts to achieve TAP are expected to be successful in patients with either a nasal or oral GT in place.