In a double-blind, randomized, placebo-controlled clinical trial, 30 healthy subjects took one of two potassium chloride preparations or placebo three times a day for 1 week with concomitant oral glycopyrrolate dosing. The upper digestive tract was endoscopically examined immediately before and after the treatment period. One subject in both of the KCl treatment groups and six subjects in the placebo group developed submucosal lesions. All lesions were minor and of limited clinical significance. There may be reason to believe that glycopyrrolate plays a role in the production of such lesions. If so, the concomitant use of glycopyrrolate in clinical trials of KCl preparations may cloud the results of such studies.