OVERVIEW: Arterial hypotension during stress echocardiography with Dobutamine (ESD) is an occasional complication with no prognostic value, but it sometimes necessitates termination of the investigation. The present study had the aim of elucidating the mechanism responsible for hypotension during ESD and proposing one or several markers for patients at risk for this complication. METHOD: One hundred and twenty consecutive patients referred for stress echocardiography (Dobutamine or cycloergometrine) were analysed. Arterial hypotension induced by Dobutamine was defined as a fall of more than 30 mmHg compared to the arterial pressure before the test or following the preceding level of Dobutamine. Concentric left ventricular hypertrophy (LVH) was defined as a left ventricular mass > 125 g/m2. RESULTS: Among the 89 patients undergoing ESD, 32 (35%) had LVH, 9 of whom (28%) had arterial hypotension, prompting termination of the examination in 4 patients. Among the 57 patients (65%) without LVH, only 2 (3%) had hypotension. All patients with LVH had normal left ventricular function at rest and excellent contractility under stress, with no sign of ischaemia. None of the 31 patients, 5 of whom had LVH, who underwent the test with cycloergometrine had hypotension. CONCLUSION: Hypotension occurring during ESD affects patients more often with LVH (p < 0.001) and excellent systolic function. We postulate that the vigorous contraction of the left ventricle with Dobutamine produces excessive stimulation of the cardiac mechanoreceptors inducing a reflex hypotension. LVH is therefore a marker for patients at risk of hypotension and effort echocardiography is an excellent alternative to this investigation.