A new non-invasive haemodynamic monitoring technique was investigated on twenty female patients submitted to gynaecological laparoscopy under general anaesthesia. Continuous aortic output was measured with an echo-Doppler oesophageal probe specially developed by the authors. Peritoneal insufflation was performed with an average of 4 +/- 0.750 l CO2 at an average insufflation rate of 0.666 l X min-1; intraperitoneal pressure increased on average by 11.57 +/- 1.60 mmHg during insufflation. Aortic output changes were related to changes in the patient's position. In initial horizontal dorsal decubitus position, average aortic output was 2.83 +/- 0.642 l X min-1. Trendelenburg position (28 +/- 2 degrees) induced a transient 9.54% increase (p less than 0.05), while a return to the horizontal position was marked by an 11.3% increase (p less than 0.01) of the aortic output. No significant change was observed during insufflation and exsufflation (-2.13 and -5.3% respectively). Mean arterial pressure rose by 16.4% after insufflation (initial values: 90 +/- 15.08 mmHg; p less than 0.01). Total vascular systemic resistances were significantly higher at the end of insufflation (2.999 +/- 376 dyn X cm X s-5; + 18.04%; p less than 0.05). Heart rate did not change significantly. Aortic output monitoring with this non-invasive, easy-to-handle technique enabled early detection of haemodynamic changes during laparoscopy. These changes frequently preceded significant blood pressure or heart rate variations.