A double-blind investigation has been carried out using three different doses (20, 35 and 50 mg) of cocaine which were sprayed onto the nasal mucous membranes of forty-five patients for nasal surgery. The cocaine was administered after induction of general anaesthesia in all cases. The 20 mg dose of cocaine dissolved in 2 ml of saline without adrenaline was found to be safe and produced adequate nasal decongestion in the absence of other predominant factors. The efficacy of cocaine and its safety with regard to systemic absorption are assessed.