Infiltration with local anaesthetics with addition of adrenaline or noradrenaline has been used since 1910 prior to skin incision for craniotomy. In a controlled series of patients scheduled for intracranial operations, systemic blood pressure was measured intra-arterially after infiltration with 15-20 ml 0.5% lignocaine with nonradrenaline 1 mu gr/ml. A marked increase in systemic blood pressure was seen (125% of values prior to infiltration). In a control series, where saline was injected, a slight fall in blood pressure was registered (p smaller than 0.01). As hypertensive episodes increase intracranial pressure in patients with impaired cerebral autoregulation, or promote the risk of haemorrhage in aneurysm surgery, this technique is considered a hazard to patients undergoing intracranial operations.