The effect of suxamethonium on serum potassium levels was studied in 20 black patients undergoing emergency surgery. All patients were resuscitated pre-operatively to achieve a normal pH (range 7.35-7.45), normal electrolyte values (potassium range 3.5-4.5 mmol/l), and an adequate circulating blood volume using the criteria of systolic blood pressure in excess of 100 mmHg and a central venous pressure maintained at more than 2 cm H2O. Suxamethonium (approximately 0.8 mg/kg) was administered during a standard rapid intubation sequence for the induction of anaesthesia. In the adequately resuscitated emergency patient an induced respiratory alkalosis may prevent the rise in serum potassium previously reported with the use of suxamethonium.