We studied the hemodynamic response to preoperative emptying of the stomach by means of a gastric tube in 20 non-fasting non-premedicated patients aged 39 (24-54) (median and quartiles) presenting for emergency surgery. Systolic and diastolic blood pressure and heart rate increased by 24.4% (P less than 0.01), 29.9% (P less than 0.01) and 36% (P less than 0.01), respectively. Arterial oxygen saturation decreased by 2.1% (P less than 0.01). The rate pressure product increased by 68% (P less than 0.01), exceeding 20,000 (mmHg.min-1) [2667 kPa.min-1] in nine patients. The cardiovascular response is of the same magnitude as reported after tracheal intubation without use of analgesics and is likely to cause cardiac ischemia and other adverse effects in patients suffering from coronary artery disease.