We have investigated manometrically wether esophageal motor response (in terms of frequency and mean pressure of propulsive and non-propulsive waves) to the instillation of saline and 0.1 N HCl into the lumen was different in normal (n = 18) and refluxing (n = 66) patients. Instillation of saline induced bursts of non-propulsive waves both in normal and refluxing patients. Additionally, it induced in the latter an increase in propulsive waves. Instillation of acid did not induce in normal subjects changes different from those generated by saline but stimulated considerably the refluxing esophagus which responded with an increased number of more powerful waves. This results suggest that refluxing esophagus is hypocontractile as compared with the healthy one and that it is awaken by acid as if it tried to improve its motor efficiency.