Intravenous administration of 0.6 mg/kg of atracurium to nine patients did not produce any significant change in intracranial, mean arterial or cerebral perfusion pressures. In another three patients, anaesthesia was induced with thiopentone 5 mg/kg after muscle relaxation with atracurium 1 mg/kg. Intracranial pressure was below pre-induction levels in two patients whose tracheas were intubated 90 seconds after atracurium. The vocal cords were not fully relaxed at 90 seconds in the third patient. Intubation at 150 seconds in this patient was associated with a rise in intracranial pressure above pre-induction values.