A modified 9-luminal manometric tube served to perfuse the esophagus with 3.2 mmolar hydrochloric acid containing 2% polyethylene glycol (PEG) and to aspirate the esophageal contents. The esophageal secretion was calculated from the PEG dilution in the aspirates. Neutral red injected intravenously reddened selectively gastric juice. Red esophageal aspirates were discarded., In 6 health subjects esophageal secretion was 1.0/+-0.2 ml/min after 1 hour perfusion. It contained 38 /+-11 mmol/l na+, 3.3/+-1.4 mmol/l K+, 27/+-6 mmol/l Cl-, and 50/+-13 mumol/l N-acetylneuraminic acid (NANA). Thus this method allows measurement of the barrier function of the esophageal mucosa.