A method of anaesthesia is described for fractional coagulation of the Gasserian ganglion. The surgical procedure demands short periods of anaesthesia alternating with periods of full consciousness, during which sensory testing is carried out. In spite of the rare possibility of a hypotensive reaction, propanidid is considered to be the drug of choice for this technique. 31 patients wih typical trigeminal neuralgia have been treated with immediate relief of symptoms, whilst 3 (10%) have been successfully re-treated after recurrence of pain paroxysms. Two patients developed lung emboli, from which they recovered, in the post-operative period, and a third patient had a non-fatal myocardial infarct a week after treatment. Alternative approaches to the problem of intermittent anaesthesia, with and without intubation, are discussed.