The incidence of oesophageal dysfunction (OD) is higher in patients with coronary heart disease (CHD) than in a population sample. The hypothesis was raised that this finding is the result of a cardio-oesophageal reflex in which afferent pain impulses from the heart trigger dysfunction in the oesophagus. Twenty-three patients with CHD were examined before and 14+/-5(S.D.) months after coronary bypass surgery. Total relief of angina pectoris was attained in 6 patients and improvement in 16. One patient deteriorated. The incidence of OD was 52% before operation and 65% at the follow-up investigation (no significant difference). Symptoms related to the oesophagus, other than chest pain, were as frequent before as after operation. The findings do not support the contention that OD in patients with CHD is caused by a cardio-oesophageal reflex.