We have measured the left ventricular (LV) end-systolic (ES) pressure-area product in 30 patients under general anaesthesia. We multiplied systolic arterial pressure with the ES cavity area obtained by transoesophageal echocardiography, and compared the product with M-mode derived ES wall stress before and during cardiovascular treatment. To attain appropriate mean arterial pressure during major non-cardiac surgery, 10 hypertensive patients required treatment with nitroglycerin, 10 septic patients received noradrenaline and 10 patients with intraoperative cardiac failure were given adrenaline. Baseline values and relative changes in the ES pressure-area product correlated well (r = 0.85 and r = 0.87; P < 0.05) with those of ES wall stress. Changes in the ES pressure-area product by more than 10% reflected ES wall stress changes with a sensitivity of 88% and a specificity of 94%. With adrenaline, the ES pressure-area product and ES wall stress did not change significantly, while systemic vascular resistance increased by 20%. The ES pressure-area product seems suitable for the detection of intraoperative LV wall stress changes.