Forty patients suffering from intractable unilateral trigeminal neuralgia involving more than one division of the trigeminal nerve were treated by percutaneous radiofrequency thermocoagulation of the trigeminal sensory root. The aim of the operation was to relieve the pain without producing dense sensory deficit in the face. This goal was achieved by making selective lesions in the sensory root with gradually increasing temperature 60 degrees C to 90 degrees C. Three to four consecutive lesions each for 60 seconds have been found to produce excellent pain relief in 77.7% with good and fair results in the rest. The recurrence rate has been found to be 15% during 2 years of follow-up. Considerable dysaesthesia was observed in 5% of cases. Corneal anaesthesia was found in 5% cases while one patient developed neuroparalytic keratitis. Transient trigeminal motor weakness was observed in 10% of patients.