The therapeutic effects of positioning and state of alertness were evaluated in 79 patients with gastroesophageal reflux (GER) and 49 nonreflux patients by extended esophageal pH monitoring during the two-hour postprandial period. The amount of GER in nonreflux patients was not significantly affected by changes in position or state or alertness whereas patients with GER demonstrated consistent decreases in the percent time and frequency of reflux episodes while asleep compared wtih being awake. In patients with GER, less reflux occurred while upright than supine during awake but not during asleep periods. The 30-degree elevated prone position was superior to the supine or upright positions while patients were awake or asleep. A beneficial effect of the 30-degree elevated supine position was not noted. Patients with respiratory disease, with severe esophagitis, or who required surgical correction of GER all responded to positioning or alertness changes in the same manner.