We compared the change in left ventricular ejection fraction during rest and exercise in 14 patients with angina pectoris and 14 patients with silent ischaemia. All patients had ischaemia defined as reversible defects at an exercise thallium myocardial scintigraphy. In the patients with angina pectoris the ejection fraction decreased from 44.0% (+/- 1 SD 13.4) at rest to 39.5% (+/- 1 SD 11.2) during exercise (p = 0.044). In the patients with silent ischaemia the ejection fraction decreased from 43.5% (+/- 1 SD 14.0) to 39.8% (+/- 1 SD 13.9) (p = 0.045). The fall in left ventricular ejection fraction in the two groups was almost identical (p = 0.77). This study confirms with a sensitive detection of transient ischaemia that silent ischaemia is accompanied with a fall in ejection fraction during exercise.